The interpretation timeline
Isaiah 43:2 Douay-Rheims

When thou shalt pass through the waters, I will be with thee, and the rivers shall not cover thee: when thou shalt walk in the fire, thou shalt not be burnt, and the flames shall not burn in thee:

A.D. 215 – 1871 10 witnesses

Patristic

before A.D. 750
215
A.D.
c. A.D. 150–215
“"Even if we cross over, they shall not slip, says the Lord." We shall not slip into corruption, we who are crossing over into incorruption, because he himself will support us. For so he himself has said and so he has willed.”
397
A.D.
Ambrose of Milan Patristic
A.D. 339–397
“We are wayfarers in this life; many walk, but it is needful that we walk aright, for then is the Lord Jesus with us, as we read, When thou passest through the waters I will be with thee, and through the rivers, they shall not overflow thee; when thou walkest through the fire thou shalt not be burned. But if a man take fire in his bosom, the fire of lust, the fire of immoderate desire he walketh not through, but burns this clothing of his soul. A good name is rather to be chosen than great riches, and loving favour than silver and gold! Faith is sufficient for itself, and in its own possession is rich enough. And to the wise man nothing is foreign, but what is contrary to virtue; wherever he goes, he finds all things to be his own. All the world is his possession, for he uses it all as if it were his own.”
Source
604
A.D.
Gregory the Great Patristic
c. A.D. 540–604
“And through the prophet the Lord promises saying, "When thou passest through the waters, I will be with thee, and the rivers shall not overflow thee." For the rivers overflow those whom the active business of this world confounds with perturbation of mind. But he who is sustained in mind by the grace of the Holy Spirit passes through the waters, and yet is not overflowed by the rivers, because in the midst of crowds of peoples he so proceeds along his way as not to sink the head of his mind beneath the active business of the world.”
Source

Scholastic

c. 1100 – 1500
1105
A.D.
Rashi Jewish
1040–1105
“When you pass through water When you passed through the Reed Sea, I was with you. and in rivers, they shall not overflow you You dwelt among the Egyptians and the heathens (peoples [: mss.]) numerous as the waters of a river, and they could not prevail against you to destroy you. when you go amidst fire In the future, “For behold, a sun is coming, burning like an oven” (Malachi 3:19), for I will cause the sun to burn upon the wicked, “and the coming sun shall burn them.” There, too, you shall not be burnt. a flame which shall burn the heathens ([mss.:] the nations), as it is said (supra 33:12): “And the peoples shall be as the burnings of lime.” That too shall not burn amidst you.”
Source
1167
A.D.
Ibn Ezra Jewish
1089–1167
“When thou passest through the waters, etc. The peoples are in Scripture compared with rivers and also with fire; comp. A fire is gone out of Heshbon (Num. 21:28). By the waters and the fire the armies of Persia and Media are meant, that were to conquer Babylon.”
1256
A.D.
Thomas Aquinas Catholic
1225–1274
“And now thus says the Lord, etc. Here he shows them the divine love through the remedies which he granted them amid their distresses. And it is divided into three parts. In the first he promises future remedies, to show his love; in the second he recalls past benefits, to confirm the promise: "thus says the Lord, who gave," etc.; in the third he excludes merits, to take away presumption: "you did not call upon me," etc. Concerning the first he does three things. First he shows toward them the privilege of divine love; second, from the promised remedies, he excludes any partnership in divine power: "all the nations are gathered together," etc.; in the third he sets forth the sign of his love: "thus says the Lord your redeemer," etc. Concerning the first, he promises them three remedies. First, sustenance in punishments, excluding fear by the divine presence: "creating you" — as to the principles of substance, Deut. 32: "he is your father," etc.; "forming" — as to the form which he gave, Gen. 1: "the Lord formed," etc.; "redeeming" — from evils, Hosea 13: "from the hand of death," etc.; and "I have called" — unto grace, Hosea 1: "I will call 'not my people,'" etc. He sets forth the promise: "when you shall pass through the waters" — the Egyptians; "the rivers" — the Chaldeans; "the fire" — the Greeks; "the flame" — the Romans. For they were not consumed entirely. Ps. 65: "we passed through fire," etc. And he assigns the reason for this: "for I am the Lord," etc., above, 12: "for he himself, God, is savior," etc. Second, he promises a commutation of punishments, namely that he will punish others in his place. And he sets forth the commutation. "I have given a propitiation" — that is, that I might be propitiated toward you, as it were by the punishments of those who provoked you to sin by the hope of their help. "Saba" — a city of Ethiopia. Prov. 11: "the just man out of distress," etc. And he assigns the reason, namely God's own love: "since you have become honorable" — that is, I have made and accounted you honorable. "For you" — for your liberation. Jer. 31: "if a son honorable to me," etc. Third, he promises them liberation of every kind from tribulations; and concerning this, three things. First he promises the benefit of liberation: "do not fear, from the east" — because they had been scattered in every direction. Above, 11: "he will gather the fugitives," etc.; Jer. 31: "behold I will bring them," etc. Second, he sets forth the merit of liberation: "and everyone who calls upon me I will bring" — "unto my glory," that he may glorify me, and I may appear glorious in him. Joel 2: "everyone whosoever shall call upon," etc. Third, he promulgates the precept of liberation. "Bring forth," O Cyrus, "outside" — outside the land of captivity — "the people," namely of the Jews. Jer. 5: "hear, foolish people," etc. "All the nations." Here he excludes any partnership in godhead. And first he shows the falsity of the other gods by way of a judgment, setting forth the nations' agreement with idols: "are gathered together" — into one error. Ps. 13: "all have gone astray," etc. — seeking a sign of godhead. "Who among you" — that is, which of your gods? Or he speaks to the idols, and seeks testimony. "Let them give witnesses," and "let them be justified" — that is, let them be justly called gods; and let the witnesses hear future things from them, and speak testimony on your behalf. Above, 41: "there is none announcing nor foretelling," etc. Second, he shows the truth of his own godhead: and first as to knowledge; second as to power, "you are witnesses," etc. Concerning the first, two things. First he gives testimony, assigning men as witnesses: "truly you are witnesses," etc.; "my servant" — the people of Jacob, or Christ. Acts 1: "you shall be witnesses to me," etc.; setting forth the manner of knowing: "that you may know" — as to those things which can be known of God through natural reason; and "that you may believe" — as to those things which are above reason; and thus "you may understand": for unless you shall have believed, you shall not understand, above, 8, according to another text. He also sets forth the saying of the witnesses, that he alone is God: "for I alone" — "I am" — "God." "The one who forms," or "the one formed" — namely, an idol — Deut. 32: "see that I am he alone," etc.; and that he alone is Lord: "I am" — singularly; "I am" — excellently, etc.; Acts 4: "there is no salvation in any other," etc. Second he gives a sign of godhead. "I have announced," etc.; "there was not" one from whom you could know. Ps. 80: "Israel, if you will hear me," etc. "You are witnesses," etc. Here he shows the truth of his godhead as to power: and first he gives testimony, "you are witnesses," etc., John 8: "I am the beginning," etc. Second he gives a sign of power in punishing: "and there is none who" out of the "hand" — as Deut. 32, Job 10; and in working, "I will work," etc., above, 14: "the Lord of hosts has decreed," etc. "Thus says the Lord," etc. Here he sets forth the sign of love: because for their sake he destroyed the Babylonians glorying in their ships, on account of the multitude of waters. "I have sent forth" — namely, wrath — Jer. 51: "the Lord has planned and has done," etc. "Thus says the Lord who gave," etc. Here he recalls past benefits, to confirm hope concerning future ones. And concerning this he does two things. First he recalls the past benefits when they went out from Egypt, in their governance. "In the sea" — the Red Sea, Exod. 14; "in the waters of the torrent" — in the Arnon, Numbers 21; in the Jordan, Joshua 3. And as to the destruction of enemies: "who brought forth the chariot" — the chariots of Pharaoh, etc., Exod. 15: "his chosen princes," etc.; "as flax" — cut off in a moment. Second he promises things much greater in the future; and concerning this he does three things. First he shows the greatness of future benefits by comparison with the former: "do not remember" — as if to say: they are not worthy to be held in memory in comparison with the future ones, Phil. 3: "forgetting indeed those things which are behind," etc.; by their newness: "behold I make new things" — unheard of, Apoc. 21: "behold I make all things new." And by their determination: "I will set in the desert" — that is, in the land of the Jews, which was formerly desert — "a way" — of those going to the festivities; "rivers" — of consolation, Ps. 106: "he turned the desert into pools," etc. And if these things are expounded literally of the liberation from the captivity of Babylon, they are said to be greater than the liberation from Egypt — not on account of greater miracles, but because the kings from whose power he liberated them were more powerful than Pharaoh; or because they came from a more distant place. But if they are referred to the liberation wrought through Christ, it is clear that nothing so admirable had preceded it in past ages. Second he shows the usefulness of the benefits among the nations: "and the beast of the field will glorify" — that is, the Gentile living beastially, converted to Christ; or those seeing how I free the Jews. Ps. 148: "beasts and all cattle," etc.; and among the Jews: "that I might give drink" — of doctrine and consolation, Deut. 7: "the Lord has chosen you," etc. Third he assigns the reason: "this people for myself" — unto my praise. Prov. 16: "all things for himself," etc. "You did not call upon me." Here he excludes the merits of the Jews for obtaining such great benefits; and concerning this, three things. First he excludes merit; second he gives room for a response, "bring me back to mind," etc.; third he removes a certain manner of responding, "your father," etc. Concerning the first, three things. First he excludes merit: "you did not call upon me" — and all these things are said because they did not offer these things to God with their whole heart, but partly to God, partly to idols; or because they conferred nothing on God; or because they did them in hope of temporal recompense; or because after the coming of Christ they were not accepted. Mal. 3: "who is there among you that would shut the doors," etc.; Ps. 49: "shall I eat," etc. Second he shows their guilt: "nevertheless, to serve" — as if to say: you have shown me servile, while, though you offended me, I did not punish. Above, 1: "they have become troublesome to me," etc. He speaks in a human manner. Third he shows the benefit given freely: "I am," etc., Ps. 24: "for your name's sake you will be propitious," etc., Ez. 36: "not for your sakes will I do this," etc. "Bring me to remembrance," etc. Here he gives room for a response. "Bring back" — as if to say: think again on what I have done for you; tell if you have anything, to excuse yourself, or to accuse me, that you may be justified, that is, that you may be judged just. Job 33: "if you have anything to say," etc. "Your father." Here he removes a certain way of responding. For they could allege the innocence of their fathers; but against this he speaks. "Father" — Adam, Gen. 3; Abraham, seeking a sign concerning God's promise, as though doubting, Gen. 15; "interpreters" — Moses and Aaron at the waters of contradiction, Num. 21; "I have profaned" — that is, I have allowed to be profaned — unto utter destruction: for all died in the desert, except Caleb and Joshua. Ps. 105: "we have sinned with our fathers," etc. (Collationes, chap. 43). The Lord frees the saints from fire: of carnal temptation, Job 31: "it is a fire even unto consumption," etc.; of temporal tribulation, Ps.: "you have tried me by fire"; of eternal damnation, Matt. 25: "depart, you cursed"; of divine indignation, Deut. 32: "a fire is kindled," etc. In which are burned: the lascivious, 1 Cor. 7: "it is better to marry," etc.; the impatient, above, 13: "their faces shall be burnt," etc.; the impenitent, Ps.: "the flame has burned up sinners"; the proud, the same: "the foundations of the mountains," etc. He also frees from waters: of pleasure, Prov. 9: "stolen waters," etc., in which they are suffocated through luxury; of cupidity, Exod. 15: "they sank as lead," etc., in which through avarice; of adversity, Ps.: "the waters have come in even unto the soul," etc., in which through impatience; of worldly power, Apoc. 17: "the waters upon which she sits," etc., in which through pride. Bring God back into memory as to: the wonders which he has done, that they be venerated, Ps.: "remember his wonders," etc.; the benefits which he gave, that thanks be rendered, Ecclus., last chapter: "I have remembered mercy," etc.; the torments which he endured, that compassion be shown, Lam. 3: "remember my poverty," etc.; the precepts which he gave, that they be observed, Ps.: "that they may be mindful," etc.”

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“When thou passest through the waters; I will be with thee,.... The Targum and Jarchi apply this to the Israelites' passage through the waters of the Red sea, as a thing past; and Kimchi to Sennacherib's army, compared to the waters of a river strong and many, Isa 8:7. Jerom says, that the Jewish writers by "waters" would have the Egyptians understood; by the "rivers", the Babylonians; by "fire", the Macedonians; and by the "flame", the Romans; which is not amiss; but rather the afflictions of God's people in general are meant by waters, as by rivers also, in the next clause: and through the rivers, they shall not overflow thee; because of the variety and multitude of them, as persecutions from men, those proud waves that go over them; the temptations of Satan, that enemy who comes in like a flood, and various others; and because of the rapidity and force of them, and their overflowing and overwhelming nature: now there are paths through which the people of God pass: their way lies through them to eternal glory; and though they are of some continuance, yet have an end, as paths have; and having a good guide, and sufficient strength given them, they wade through them safely; for they do not and shall not "overflow" them, so as to cause their faith utterly to fail, or to separate them from the love of God, or so as to destroy them; for though they come nigh them, and upon them, and may greatly affect and distress them, yet shall not hurt them, but turn to their advantage; for their God is with them, to sympathize with them, to comfort and revive them, to teach and instruct them by their afflictions, and to sanctify them to them, as well as to support and bear them up under them, and to deliver out of them: when thou walkest through the fire, thou shalt not be burnt: neither shall the flame kindle upon thee; afflictions are compared to fire and flames, because very grievous and troublesome to the flesh; and because of the apprehensions of God's wrath in them sometimes; and because of their trying nature; grace is tried by them as gold and silver in the fire; but yet the saints are not consumed by them, they lose nothing but their dross; their principles and profession are tried, and they are supported through all; which has been abundantly verified in the martyrs of Jesus; see Psa 66:12.”
Source
1849
A.D.
1774–1849
“Waters. In every emergency, God will protect thee, (Calmet) as he did the three children. [Daniel iii.] (Haydock) — He will suffer none to perish, without their own fault. Hence the Church still continues pure. (Worthington)”
1863
A.D.
1871
A.D.
1871
“rivers . . . not overflow thee--so in passing Jordan, though at its "overflow," when its "swellings" were especially dangerous (Jos 3:15; Jer 12:5). waters . . . fire--a proverbial phrase for the extremest perils (Psa 66:12; also Psa 138:7). Literally fulfilled at the Red Sea (Exo 14:21-22), and in the case of the three youths cast into the fiery furnace for conscience' sake (Dan 3:25, Dan 3:27).”
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.