The interpretation timeline
1 Peter 4:8 Douay-Rheims

But before all things have a constant mutual charity among yourselves: for charity covereth a multitude of sins.

A.D. 99 – 1871 10 witnesses

Patristic

before A.D. 750
99
A.D.
Clement of Rome Patristic
d. A.D. 99
“Love unites us to God. Love covers a multitude of sins. Love bears all things, is long-suffering in all things. There is nothing base, nothing arrogant in love. Love admits of no schisms: love gives rise to no seditions: love does all things in harmony. By love have all the elect of God been made perfect; without love nothing is well-pleasing to God.”
Source
215
A.D.
c. A.D. 150–215
“This is love, to love God and our neighbour. This conducts to the height which is unutterable. "Love covers a multitude of sins. Love beareth all things, suffereth all things." Love joins us to God, does all things in concord. In love, all the chosen of God were perfected. Apart from love, nothing is well pleasing to God.”
Source
220
A.D.
Tertullian Patristic
c. A.D. 150–220
“" For, strictly speaking, there cannot any longer be reckoned ought against the martyrs, by whom in the baptism (of blood) life itself is laid down. Thus, "love covers the multitude of sins; " and loving God, to wit, with all its strength (by which in the endurance of martyrdom it maintains the fight), with all its life (which it lays down for God), it makes of man a martyr.”
Source
397
A.D.
Ambrose of Milan Patristic
A.D. 339–397
“So then he who sins loves not, for charity shall cover the multitude of sins. But if charity exclude the desire of sin, it excludes also fear, charity then is full of perfect faith.”
461
A.D.
Leo the Great Patristic
c. A.D. 400–461
“Nothing is stronger against the wiles of the devil, dearly beloved, than the kindness, mercy and generosity of love, through which every sin is either avoided or conquered.”

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“And above all things have fervent charity among yourselves,.... Not but that charity, or love, is to be exercised towards all men, even towards enemies, but more especially towards the saints, and that under such a consideration in which it cannot be exercised towards others; namely, as their brethren in Christ, and as belonging to him, as the children of God, as redeemed by Christ, and sanctified by the Spirit; and these not only such as are of the same nation, and belong to the same particular church and community, or of the same denomination, but all the saints everywhere, whether Jews or Gentiles, or of whatsoever name, and in whatsoever state and condition: and this love ought to be mutual and reciprocal, and to be warm and fervent, and not lukewarm and indifferent, as it too often is; and should be constant, "continued", and "perpetual", as the Vulgate Latin and Arabic versions here read: and this the apostle exhorts to above all things else; since outward sobriety, and watchings, and prayer, and all other duties, are nothing without this; this is the sum and substance of the law, and the fulfilling of it; and without this a mere knowledge of the Gospel, and a profession of it, are in vain, and therefore in the first place to be attended to. And especially for the following reason, for charity shall cover the multitude of sins; referring to Pro 10:12 not a man's own sins, but the sins of others; and not from the sight of God, for from that only the blood and righteousness of Christ cover sins, even all the sins, the whole multitude of the sins of God's elect; but from the sight of men, both of those against whom they are committed, and others; since charity, or true love, thinks no ill, but puts the best constructions upon the words and actions of fellow Christians, and does not take them up, and improve and exaggerate them, but lets them lie buried in oblivion: it takes no notice of injuries, offences, and affronts, but overlooks them, bears with them, and forgives them, so that they are never raked up, and seen any more; which prevents much scandal, strife, and trouble. The Alexandrian copy, and some others, and the Vulgate Latin, Syriac, and Arabic versions, read, "covereth", as in Pro 10:12.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“Have fervent charity - Αγαπην εκτενη· Intense love; for love shall cover a multitude of sins. A loving disposition leads us to pass by the faults of others, to forgive offenses against ourselves, and to excuse and lessen, as far as is consistent with truth, the transgressions of men. It does not mean that our love to others will induce God to pardon our offenses. See the note on Jam 5:20.”
Source
1849
A.D.
1774–1849
“Charity covereth a multitude of sins. It is a great means to atone for them; or it may signify, that a charitable mind excuses many sins in others. Wi.”
1871
A.D.
1871
“above all things--not that "charity" or love is placed above "prayer," but because love is the animating spirit, without which all other duties are dead. Translate as Greek, "Having your mutual (literally, 'towards yourselves') charity intense." He presupposes its existence among them; he urges them to make it more fervent. charity shall cover the multitude, &c.--The oldest manuscripts have "covereth." Quoted from Pro 10:12; compare Pro 17:9. "Covereth" so as not harshly to condemn or expose faults; but forbearingly to bear the other's burdens, forgiving and forgetting past offenses. Perhaps the additional idea is included, By prayer for them, love tries to have them covered by God; and so being the instrument of converting the sinner from his error, "covereth a (not 'the,' as English Version) multitude of sins"; but the former idea from Proverbs is the prominent one. It is not, as Rome teaches, "covereth" his own sins; for then the Greek middle voice would be used; and Pro 10:12; Pro 17:9 support the Protestant view. "As God with His love covers my sins if I believe, so must I also cover the sins of my neighbor" [LUTHER]. Compare the conduct of Shem and Japheth to Noah (Gen 9:23), in contrast to Ham's exposure of his father's shame. We ought to cover others' sins only where love itself does not require the contrary.”
Source

Undated

date unknown
date
unknown
Glossa Ordinaria Medieval
“Having continual charity. He who through charity admonishes his neighbour, rebukes him, etc., up to although it cannot always be shown in public.”
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.