The interpretation timeline
Psalm 101:9 Douay-Rheims

All the day long my enemies reproached me: and they that praised me did swear against me.

A.D. 386 – 1875 9 witnesses

Patristic

before A.D. 750
386
A.D.
Cyril of Jerusalem Patristic
A.D. 313–386
“So then the prophet comforted David as we have seen, but that blessed man, though he received most gladly the assurance, "The Lord has put away your sin," did not, king as he was, draw back from penitence. Indeed he put on sackcloth in place of his purple robe, and the king sat in ashes on the bare earth instead of on his gilded throne. And in ashes he did not merely sit but took them for eating, as he himself says, "I have eaten ashes as if bread and mingled my drink with weeping." His lustful eye he wasted away with tears; as he says, "Every night I wash my bed and water my couch with my tears." And when his courtiers exhorted him to take bread, he would not, but he prolonged his fast for seven whole days. Now if a king was apt to make confession after this manner, should not you, as a private person, make your confession? Again, after Absalom's rebellion, when David was in flight, with many roads to choose from before him, he chose to make his escape by the Mount of Olives, as good as invoking in his own mind the Deliverer who should from there ascend into the heavens. And when Shimei cursed him bitterly, he said, "Let him be." For he knew that forgiveness is for those who forgive.”
Source
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“And after humility of mind, there is need of intense prayers, of many tears, tears by day and tears by night, for, he says, "every night will I wash my bed, I will water my couch with my tears. I am weary with my groaning." And again, "For I have eaten ashes as if bread and mingled my drink with weeping."”
428
A.D.
Paulinus of Milan Patristic
c. A.D. 370–428
“Indeed, to the penitent confession alone does not suffice, unless correction of the deed follows, with the result that the penitent does not continue to do deeds that demand repentance. He should even humble his soul just as holy David, who, when he heard from the prophet, "Your sin is pardoned," became more humble in the correction of his sin, so that "he did eat ashes like bread and mingled his drink with weeping."”
Source
523
A.D.
c. A.D. 450–523
“And again, he teacheth thee also concerning that which he took as a preparation for his meat, saying, "For I have eaten ashes like bread:" these were the condiments and dainties which were laid upon the table of this righteous king when he ate his food. Listen also concerning the strained wine which he drank: "I have mingled my drink with tears." Behold the meat and drink of the righteous king! He fed himself upon ashes, and his drink was tears of suffering. What disciple on hearing these things will not break his heart in sorrow for his slothful life, if indeed he be a disciple?”
Source

Scholastic

c. 1100 – 1500
1105
A.D.
Rashi Jewish
1040–1105
“those who scorn me Heb. מהוללי, those who scorn me, an expression of mockery. swear by me They saw my misfortune and they swear by me and say, “If it is not so, what happened to Israel should happen to me.” “So may the Lord do to me as to Israel.””

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Because of thine indignation and thy wrath,.... This was the burden of his complaint, what gave him the greatest uneasiness; not so much the reproach of his enemies, and his other outward afflictions, as the sense he had of God's wrath and indignation. The people of God are as deserving of his wrath as others; and when they are awakened to a sense of sin and danger, or the law enters into their consciences, it works wrath there, and leaves nothing but a fearful looking for of judgment and fiery indignation, till comfort is given; and under afflictive providences they are very ready to conclude, that the wrath of God is upon them; but this is only their apprehension of things; it is not in reality: for God has not appointed them to wrath, and has swore he will not be wroth with them; Christ has bore it for them, in their room and stead; and being justified by his blood and righteousness, they are saved from it; but then the sense they have of it is very terrible, and there is no rest, peace, and comfort in their souls, while under the apprehensions of it: for thou hast lifted me up, and cast me down; as a man that, in wrestling, has the advantage of his antagonist, lifts him up as high as he can, that he may throw him with the greater force upon the ground; in like manner the psalmist thought the Lord was dealing with him: or this may express his changeable state and condition, sometimes lifted up, and sometimes cast down, and which is the case of every believer, more or less; all have their liftings up, and their castings down: when God first calls them by his grace, he raises them from a low estate, lifts them up out of an horrible pit, takes them from the dunghill, sets them among princes to inherit the throne of glory: when he comforts them with the consolations of his Spirit, he is the lifter up of their heads; when he grants his presence, and lifts up the light of his countenance: when he discovers his love, and makes their mountain to stand strong; when he shows them their interest in himself, as their covenant God, in Christ, as their Redeemer and Saviour, and grants them the communion of the Holy Ghost; and when their graces are in lively exercise, then is it a time of lifting up: and they are cast down when corruptions prevail, when grace is weak, when God hides his face, and when afflictions lie heavy on them: this was now the case of the psalmist, and perhaps the remembrance of his liftings up in former times was an aggravation of it.”
Source
1849
A.D.
1774–1849
“Against me. To kill me, (Acts xxiii. 12.) or to prove my guilt. (Calmet) — They are my sworn enemies, (Worthington) who formerly seemed my friends. (Haydock)”
1863
A.D.
1796–1863
“The Septuagint assumes that those who once flattered him, now swore against him. The Hebrew term may be understood of furious opponents. With different punctuation it may bear either meaning. Olshausen suspects that the text has suffered.”
1875
A.D.
Keil & Delitzsch Lutheran
1861–1875
“Ashes are his bread (cf. Lam 3:16), inasmuch as he, a mourner, sits in ashes, and has thrown ashes all over himself, Job 2:8; Eze 27:30. The infected שׁקּוי has שׁקּוּ = שׁקּוּו for its principal form, instead of which it is שׁקּוּי in Hos 2:7. "That Thou hast lifted me up and cast me down" is to be understood according to Job 30:22. First of all God has taken away the firm ground from under his feet, then from aloft He has cast him to the ground - an emblem of the lot of Israel, which is removed from its fatherland and cast into exile, i.e., into a strange land. In that passage the days of his life are כּצל נטוּי, like a lengthened shadow, which grows longer and longer until it is entirely lost in darkness, Psa 109:23. Another figure follows: he there becomes like an (uprooted) plant which dries up.”
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.