The interpretation timeline
Jeremiah 20:12 Douay-Rheims

And thou, O Lord of hosts, prover of the just, who seest the reins and the heart: let me see, I beseech thee, thy vengeance on them: for to thee I have laid open my cause.

A.D. 215 – 1871 4 witnesses

Patristic

before A.D. 750
215
A.D.
c. A.D. 150–215
“For God does not hold out against his children when they beg his pity. And for you he will pray purely, held in high honor as an angel of God, and grieved not by you but for you. This is sincere repentance. "God is not mocked," nor does he give heed to vain words. For he alone searches the innermost recesses of the heart, and hears those that are in the fire, and listens to those who supplicate in the whale's belly and is near to all who believe, and far from the ungodly if they do not repent.”
Source

Scholastic

c. 1100 – 1500
1252
A.D.
Thomas Aquinas Catholic
1225–1274
“Here is set forth the prophet's complaint: and first he laments the office enjoined upon him, second the origin of his birth. Concerning the first, two things: first he laments the office enjoined upon him on account of the mockery that followed; second, on account of persecution, at the place, for I have heard the reproaches of many. Concerning the first, three things. First, as if complaining, he makes known the manner of the injunction, "you have deceived"; that is, I received from your words an occasion of deception: for I believed that I would prophesy against the nations, and not against the Jews, from whom I suffer persecution. But he does not mean to impute the crime of deception to God, for that would be blasphemy. "You have prevailed," imposing the office upon me though I resisted, as above, 1. And this especially because he did not see the fruit of his preaching. Isaiah 49: I have labored in vain, without cause and in vain have I spent my strength. Second, he sets forth the outcome of his preaching, setting forth the mockery: "I have become a derision" (...) all of them mock, wrinkling the nose, publishing abroad their derision. Lamentations 3: I have become a derision to all my people, their song all the day. And he assigns the reason, setting forth the word of his preaching, by which he openly rebuked their faults and threatened punishments: for now for a long time I have been crying out, proclaiming iniquity and devastation, which nevertheless has not yet come. Isaiah 16: to those who rejoice over the wall of baked brick, speak their wounds. And the resulting reproach: "and the word of the Lord has become to me a reproach," that is, a cause of reproach. Acts 26: Festus said to Paul: much learning has brought you to madness. Third, he renounces the office enjoined upon him: "and I said." And first he casts off the office: "I will not remember," that is, I will no longer think to speak to the people. For he did not wish to scatter pearls before swine. Matthew 7: do not give what is holy to dogs. Second, he resumes the office he had cast off: "and it became as a fire"; for the more one abstains outwardly from words, the more he feels within the fervor of love. Psalm 38: my heart grew hot within me, and in my meditation a fire shall burn. "In the bones," in the inmost parts of the mind, "I fainted," from my purpose, not enduring to bear the inward burning, "for I have heard the reproaches of many." Here he complains of the office he had undertaken, from the fact that he was enduring persecutions. And first is set forth the persecution of his adversaries: and first he sets forth the multitude of those persecuting him, "of many," against whom resistance is not possible. "Persecute ye"; in which their conspiracy is noted. He also sets forth their familiarity: "from all the men who were at peace with me"; in which the imminent danger is noted. Obadiah: all the men of your covenant have deceived you, the men of your peace have prevailed against you. Second, the prophet's comforting is set forth, setting forth the divine help: "but the Lord is with me," to defend me. Isaiah 50: the Lord God is my helper, and therefore I am not confounded. And his office: "and therefore they shall fall," because they persecute. Isaiah 40: the young shall faint and labor, and the youths shall fall by infirmity. "They shall be confounded," because they have spoken reproaches; "because they did not understand," that is, they were unwilling to understand, the reproach, of eternal damnation, or of future captivity. Psalm 39: let them be confounded, and let them fear who seek my soul to take it away. Third, the petition is set forth: where he seeks to win goodwill, commending justice: "the tester," that is, the approver or examiner and discerner, "of knowledge," who sees the reins, as to the affections, and the hearts, as to the thoughts. Above, 17: I the Lord search the heart, and try the reins, who give to each according to his way, et cetera. He asks for vengeance: "let me see, I beseech you, my vengeance upon them"; he assigns the cause: "for to you have I revealed," not to one ignorant of this, but placing my whole cause in you. Above, 11: for to you have I revealed my cause. Fourth, the giving of thanks is set forth, "sing to the Lord." Psalm 71: for he has delivered the poor from the mighty, the poor man who had no helper.”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“But, O Lord, that triest the righteous, and seest the reins and the heart,.... That tries the cause of the righteous, and vindicates them, rights their wrongs, and does them justice; being the omniscient God, the seer and searcher of the hearts and reins; who knows the uprightness of their hearts, as well as their ways, and the sincerity of their affections: or that tries the faith and patience of the righteous, their constancy and integrity; and upon trial finds that their affections are real, and their souls sincere; let me see thy vengeance on them; his enemies and persecutors; he does not seek vengeance himself, but desires it of the Lord; he does not ask to see his vengeance, but the Lord's vengeance on them, what he thought was just and proper to inflict on them; he knew that vengeance belonged to the Lord, and therefore left it with him, and prayed for it from him. The Targum is, "let me see the vengeance of thy judgments on them;'' for unto thee have I opened my cause; or "revealed", or "made it manifest" (k); this he did in prayer, at this time, when he laid before the Lord his whole case, and appealed and applied to him for justice, who judgeth righteous persons, and judgeth righteously. (k) "revelavi causam meam", Junius & Tremellius, Piscator. So Schmidt.”
Source
1871
A.D.
1871
“triest the righteous--in latent contrast to the hasty judgments of men (Jer 11:20; Jer 17:10). opened--that is, committed (compare Kg2 19:14; Psa 35:1).”
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.