The interpretation timeline
Isaiah 58:5 Douay-Rheims

Is this such a fast as I have chosen: for a man to afflict his soul for a day? is this it, to wind his head about like a circle, and to spread sackcloth and ashes? wilt thou call this a fast, and a day acceptable to the Lord?

A.D. 435 – 1875 8 witnesses

Patristic

before A.D. 750
435
A.D.
John Cassian Patristic
c. A.D. 360–435
“You see then that fasting is certainly not considered by the Lord as a thing that is good in its own nature, because it becomes good and pleasing to God not by itself but by in conjunction with other works. Again, in light of surrounding circumstances it may be regarded as not merely vain but actually hateful, as the Lord says: "When they fast, I will not hear their prayers."”
Source

Scholastic

c. 1100 – 1500
1105
A.D.
Rashi Jewish
1040–1105
“Is it to bend Heb. הֲלָכֹף. This ‘hey’ is the interrogative. That is to say, “Perhaps I require bending the head like a fishhook (כְּאַגְמֹן)?” אַגְמֹן is a sort of bent needle with which they catch fish, and they call it ajjm in O.F. Will you call this a fast Heb. הֲלָזֶה. An interrogative form. Therefore, the ‘hey’ is punctuated with a ‘hataf-pattah.’”
Source
1167
A.D.
Ibn Ezra Jewish
1089–1167
“A day for a man to afflict his soul. Repetition of the same idea (a fast) in other words. לכוף To bow down. It is a verb ע״ע similar in form to לקב to curse (Num. 23:11). אנמן Bulrush. A tender plant, that bends its top; it is well known. יַצִּיעַ To spread. The Dagesh in צ compensates for the omission of the radical ;י comp. אצרך I form thee (Jer. 1:5); the full form is יַיְצִיעַ, and its meaning is to place as a couch; comp. יצע was spread (Est. 4:3)”
Source
1256
A.D.
Thomas Aquinas Catholic
1225–1274
“Cry out, do not cease. Here he excludes the useless remedy by which they wished to prepare themselves for salvation. And first he enjoins the office of denunciation, setting down the manner of denouncing: that it be loud, without a fear that weighs down: cry out. Above, 40: lift up your voice with strength, you who bring good tidings to Zion. That it be continuous: do not cease. Below, 62: upon your walls, Jerusalem, I have appointed watchmen; all day and all night they shall not be silent. That it be clear and open, as a trumpet. Hosea 8: let there be a trumpet in your throat. And the word of denunciation: declare crimes — as to the greater ones; sins — as to the common ones. Above, 16: to those who rejoice over the walls of baked brick, speak of their wounds. Secondly the prophet excludes, in the person of the Lord, the useless remedy: for indeed me. And concerning this he does two things. First he excludes the remedy in which they trusted; secondly he exhorts to those things in which they were lacking: is not this. Concerning the first, two things. First he shows the presumption of their confidence as to three things in which they trusted: namely, in the inquiry of sacred knowledge: for indeed they seek me — in the Scriptures — my ways, my precepts and my wills, as a nation, that is, as if they were prepared to do them. Ezekiel 33: they say, one to another. Again in prayer: they ask of me judgments, that is, that I should judge for them against their adversaries, to draw near, with the mouth. Above, 29: this people draws near with its mouth. Again they trusted in the observance of fasts: why have we fasted, and you have not regarded it, as if it were pleasing; we have humbled ourselves — as to the circumstance surrounding the fast, in exterior humiliation — you have not known, with the knowledge of approval. Malachi 3: vain is he who serves God: and what profit is it, that we have kept his precepts? Secondly he shows the reprobation of the goods just mentioned. And first the cause of the reprobation, which is the fault of pleasure: behold, in the day — the will, in those things which please the flesh. Ecclesiasticus 18: go not after your lusts. Likewise the fault of cruelty: and all debtors — literally, so that they might persist for a long time in pursuing lawsuits, or with reference to what follows from it. James 4: you quarrel and you fight. Likewise the fault of vanity: do not fast that you may be heard — for the sake of human praise. Matthew 6: but when you pray, enter into your chamber, and having shut the door, pray to your Father. Or, that it may be heard; that is, if you wish that your prayer be heard by God. Psalm 101: Lord, hear my prayer, and let my cry come to you. Secondly he shows the insufficiency of the goods: is such — because God does not choose your punishment for its own sake, nor for the affliction of the flesh, which he touches in what he says: through the day, the whole day, to afflict. Nor as to the abjection of exterior humility, which he touches in what he says, as a circle; that is, bowing the head to the feet, or turning it about, as monks do, not insofar as it is ordered to the virtue of the mind. Matthew 6: when you fast, do not become sad like the hypocrites. Joel 2: rend your hearts, and not your garments. Is not this. Here he applies useful counsel: and first as to the zeal of piety toward one's neighbor; secondly as to the worship of religion toward God, if you turn away. Concerning the first he does two things. First he sets down the counsel of piety, that they should give up calumny: bonds — false causes, by which they cunningly bound the poor as usurers do; bundles — the same, weighing down, as to the penalties to which they bound them. Who are broken — by long servitude; burden — of servitude. Matthew 23: they bind heavy and unbearable burdens; but with their own finger they are unwilling to move them. And that they may attend to mercy, exhorting to mercy: as to the hungry, break — that is, even if you have but little; as to the wandering, and the needy; as to the naked, when you see. Job 31: if I have denied what they wished. And he sets down the cause of the exhortation: and the flesh — because, namely, it is of the same species as you. Job 5: visiting your species. Secondly he shows the fruit of the counsel: and it shall break forth. And first as to the efficacy of merits. Then as to the works of virtue: as the morning, your light; that is, your merits shall clearly appear in their rewards, which now you complain are not regarded by the Lord. It shall gather — from captivity, or in the protection of mercy. Psalm 36: he will bring forth your justice as the light. Then as to the support of prayer: then you shall call upon. Above, 30: at the voice of your cry, as soon as he hears it, he will answer you. Secondly as to the attainment of goods. And first he resumes the merit: if you take away the chain — with which you oppress the poor; to stretch out the finger — by detracting and threatening; when you shall have poured out — through compassion; you shall have filled — through the supplying of necessities. Secondly he promises the reward: it shall rise. And first as to the multiplication of goods, setting down deliverance from evils: it shall rise in the darkness — adversity shall be changed into the light of prosperity, ignorance into the light of knowledge, or sin into the light of knowledge, as to spiritual things. And rest — as to temporal evils. 2 Corinthians 4: God, who said, out of darkness. The multiplication of interior spiritual goods: he will fill with splendors — namely, with virtues or consolations; and your bones — as to bodily things. Ecclesiasticus 30: a splendid and good heart. And of exterior goods: and you shall be as a garden — on account of prosperity, or the unfailingness of all goods. Numbers 24: how beautiful are your tabernacles, Jacob. Secondly as to the rebuilding of the homeland: and there shall be built, after the return from captivity, of the ages — that is, the cities deserted in former ages — you shall raise up, by building upon the ancient foundations. Above, 44: who say to Jerusalem, you shall be inhabited; and to the cities of Judah, you shall be built. Thirdly as to the restoration of reputation: and you shall be called the builder of hedges, that is, of the obstacles of sin; of iniquities; or into rest — namely, converting the paths of sin into rest. Hosea 2: I will hedge up your ways with thorns. If you turn away. Here he sets down counsel as to the worship of religion in the observance of the sabbath. And first he sets down the counsel: the foot — lest you do forbidden works. You shall be called the sabbath, that is, one celebrating this sabbath, as to the exercise of good works. Exodus 20: remember to keep holy the sabbath day. Another text has: you shall have called; and the sense is the same. Secondly he sets down the fruit: then you shall delight — as to spiritual goods; I will lift you up — by bringing you back into your land, which is mountainous; I will feed you — as to the enjoyment of the goods of the land. Job 22: then you shall abound with delights over the Almighty. Note, on that word, lift up like a trumpet, that preaching is a trumpet. First, because it rouses to the state of life. 1 Corinthians 15: for the trumpet shall sound, and the dead shall rise incorrupt. Secondly, because it exhorts to battle. 1 Corinthians 14: if the trumpet gives an uncertain sound, who will prepare himself for battle? Thirdly, because it announces the approach of a man. Above, 27: it shall be sounded with trumpets. Fourthly, because it calls to counsel. Hosea 8: let there be a trumpet in your throat. Fifthly, because it invites to a feast. Psalm 80: blow the trumpet at the new moon. Likewise note, on that passage, if you take away from your midst the chain, what a chain is. First, of piety. Ephesians, last chapter: for which I perform an embassy in this chain. Secondly, of iniquity. Wisdom 17: for they were all bound together by one chain of darkness. Thirdly, of poverty. Job 36: if they shall have been bound. Fourthly, of servitude. Jeremiah 28: wooden chains. Fifthly, of prison. Ecclesiastes 4: for out of prison and chains one sometimes comes forth to a kingdom.”

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Is it such a fast that I have chosen?.... That is, can this be thought to be a fast approved of by me, and acceptable to me, before described, and is as follows: a day for a man to afflict his soul? only to appoint a certain day, and keep that, by abstaining from bodily food, and so for a short time afflict himself; or only after this manner to afflict himself, and not humble himself for his sins, and abstain from them, and do the duties of justice and charity incumbent on him: is it to bow down his head as a bulrush; when it is moved with the wind, or bruised, or withered; as if he was greatly depressed and humbled, and very penitent and sorrowful. The Syriac version renders it, "as a hook"; like a fish hook, which is very much bent; so Jarchi interprets the word: and to spread sackcloth and ashes under him? which were ceremonies used in times of mourning and fasting; sometimes sackcloth was put on their loins, and ashes on their heads; and sometimes these were strewed under them, and they laid down upon their sackcloth, which, being coarse, was uneasy to them, and rolled themselves in ashes, as expressive of their meanness and vileness: wilt thou call this a fast, and an acceptable day to the Lord? does this deserve the name of a fast? or can it be imagined that such a day so spent, can be agreeable to God? that such persons and services will be accepted of by him? or that hereby sin is atoned for, and God is well pleased, and will show his favour and good will, and have respect to such worshippers of him? no, surely.”
Source
1849
A.D.
1774–1849
“Circle. They affected extreme debility, Matthew vi. 16. (Calmet) — Ashes. These external marks of penance are not condemned, but the want of corresponding sentiments. (Haydock) — Protestants would hence infer that fasting from flesh is not requisite, or a religious worship. But St. Jerome shews the contrary, provided it be joined with the observance of other commandments, as the saints and Christ himself have shewn us. (Worthington)”
Source
1871
A.D.
1871
“for a man to afflict his soul--The pain felt by abstinence is not the end to be sought, as if it were meritorious; it is of value only in so far as it leads us to amend our ways (Isa 58:6-7). bow . . . head . . . sackcloth--to affect the outward tokens, so as to "appear to men to fast" (Mat 6:17-18; Kg1 21:27; Est 4:3).”
Source
1875
A.D.
Keil & Delitzsch Lutheran
1861–1875
“Whilst the people on the fast-day are carrying on their worldly, selfish, everyday business, the fasting is perverted from a means of divine worship and absorption in the spiritual character of the day to the most thoroughly selfish purposes: it is supposed to be of some worth and to merit some reward. This work-holy delusion, behind which self-righteousness and unrighteousness were concealed, is met thus by Jehovah through His prophet: "Can such things as these pass for a fast that I have pleasure in, as a day for a man to afflict his soul? To bow down his head like a bulrush, and spread sackcloth and ashes under him - dost thou call this a fast and an acceptable day for Jehovah? Is not this a fast that I have pleasure in: To loose coils of wickedness, to untie the bands of the yoke, and for sending away the oppressed as free, and that ye break every kind of yoke? Is it not this, to break thy bread to the hungry, and to take the poor and houseless to thy home; when thou seest a naked man that thou clothest him, and dost not deny thyself before thine own flesh?" The true worship, which consists in works of merciful love to one's brethren, and its great promises are here placed in contrast with the false worship just described. הכזה points backwards: is such a fast as this a fast after Jehovah's mind, a day on which it can be said in truth that a man afflicts his soul (Lev 16:29)? The ה of הלכף is resumed in הלזה; the second ל is the object to תּקרא expressed as a dative. The first ל answers to our preposition "to" with the infinitive, which stands here at the beginning like a casus absol. (to hang down; for which the inf. abs. הכפוף might also be used), and as in most other cases passes over into the finite (et quod saccum et cinerem substernit, viz., sibi: Ges. 132, Anm. 2). To hang down the head and sit in sackcloth and ashes - this does not in itself deserve the name of fasting and of a day of gracious reception (Isa 56:7; Isa 61:2) on the part of Jehovah (ליהוה for a subjective genitive). Isa 58:6 and Isa 58:7 affirm that the fasting which is pleasant to Jehovah consists in something very different from this, namely, in releasing the oppressed, and in kindness to the helpless; not in abstinence form eating as such, but in sympathetic acts of that self-denying love, which gives up bread or any other possession for the sake of doing good to the needy. (Note: The ancient church connected fasting with almsgiving by law. Dressel, Patr. Ap. p. 493.) There is a bitter irony in these words, just as when the ancients said, "not eating is a natural fast, but abstaining form sin is a spiritual fast." During the siege of Jerusalem by the Chaldeans a general emancipation of the slaves of Israelitish descent (who were to be set free, according to the law, every three years) was resolved upon and carried out; but as soon as the Chaldeans were gone, the masters fetched their liberated slaves back into servitude again (Jer 34:8-22). And as Isa 58:6 shows, they carried the same selfish and despotic disposition with them into captivity. The זה which points forwards is expanded into infin. absolutes, which are carried on quite regularly in the finite tense. Mōtâh, which is repeated palindromically, signifies in both cases a yoke, lit., vectis, the cross wood which formed the most important part of the yoke, and which was fastened to the animal's head, and so connected with the plough by means of a cord or strap (Sir. 30:13; 33:27). (Note: I have already observed at Isa 47:6, in vindication of what was stated at Isa 10:27, that the yoke was not in the form of a collar. I brought the subject under the notice of Prof. Schegg, who wrote to me immediately after his return from his journey to Palestine to the following effect: "I saw many oxen ploughing in Egypt, Palestine, Syria, and the neighbourhood of Ephesus; and in every case the yoke was a cross piece of wood laid upon the neck of the animal, and fastened to the pole of the plough by a cord which passed under the neck of the animal.") It is to this that אגדּות, knots, refers. We cannot connect it with mutteh, a state of perverted right (Eze 9:9), as Hitzig does. רצוּצים are persons unjustly and forcibly oppressed even with cruelty; רצץ is a stronger synonym to עשׂק (e.g., Amo 4:1). In Isa 58:7 we have the same spirit of general humanity as in Job 31:13-23; Eze 18:7-8 (compare what James describes in Jam 1:27 as "pure religion and undefiled"). לחם (פרשׂ) פרץ is the usual phrase for κλᾶν (κλάζειν) ἄρτον. מרוּדים is the adjective to עניּים, and apparently therefore must be derived from מרד: miserable men who have shown themselves refractory towards despotic rulers. But the participle mârūd cannot be found elsewhere; and the recommendation to receive political fugitives has a modern look. The parallels in Lam 1:7 and Lam 3:19 are conclusive evidence, that the word is intended as a derivative of רוּד, to wander about, and it is so rendered in the lxx, Targ., and Jerome (vagos). But מרוד, pl. מרוּדים, is no adjective; and there is nothing to recommend the opinion, that by "wanderers" we are to understand Israelitish men. Ewald supposes that מרוּדים may be taken as a part. hoph. for מוּרדים, hunted away, like הממותים in Kg2 11:2 (Keri המּמתים); but it cannot be shown that the language allowed of this shifting of a vowel-sound. We prefer to assume that מרוּדים (persecuted) is regarded as part. pass., even if only per metaplasmum, from מרד, a secondary form of רוּד (cf., מכס, מלץ, מצח, makuna). Isa 58:7 is still the virtual subject to אבחרהוּ צום. The apodosis to the hypothetical כּי commences with a perf. consec., which then passes into the pausal future תתעלּם. In hsilgnE:egaugnaL&מבשׂרך (from thine own flesh) it is presupposed that all men form one united whole as being of the same flesh and blood, and that they form one family, owing to one another mutual love.”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.