The interpretation timeline
Acts 4:20 Douay-Rheims

For we cannot but speak the things which we have seen and heard.

A.D. 407 – 1871 5 witnesses 7 excerpts

Patristic

before A.D. 750
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“"But Peter and John answered and said unto them, Whether it be right in the sight of God to hearken unto you more than unto God, judge ye. For we cannot but speak the things which we have seen and heard. So when they had further threatened them, they let them go, finding nothing how they might punish them, because of the people." The miracles shut their mouths: they would not so much as let them finish their speech, but cut them short in the middle, most insolently. "And Peter and John answered and said unto them, Whether it be right in the sight of God to hearken unto you more than unto God, judge ye." When the terror was abated (for that command was tantamount to their being dismissed), then also the Apostles speak more mildly: so far were they from mere bravery: "Whether it be right," says he: and "We cannot but speak." "Whether it be right in the sight of God to obey you rather than God." Here by "God" they mean Christ, for He it was that commanded them. And once more they confirm the fact of His Resurrection. "For we cannot but speak the things we have seen and heard:" so that we are witnesses who have a right to be believed. Already these as martyrs have borne testimony: set in the battle against all, they said, "We cannot but speak the things we have seen and heard." If the things we speak be false, reprehend them; if true, why hinderest thou? Such is philosophy! Those, in perplexity, these in gladness: those covered with exceeding shame, these doing all with boldness: those in fear, these in confidence. For who, I would ask, were the frightened? those who said, "That it spread no further among people," or these who said, "we cannot but speak the things we have seen and heard?" And these had a delight, a freedom of speech, a joy surpassing all; those a despondency, a shame, a fear; for they feared the people. But these were not afraid of those; on the contrary, while these spake what they would, those did not what they would. Which were in chains and dangers? was it not these last?”
Source
“For better than all others he knows the nature of things. He knows that fierceness is not quenched by fierceness but by meekness. If you wish to see this in action, read the book of the Acts of the apostles and you will see how often, when the people of the Jews was rebelling and sharpening their teeth, these men, imitating the dove and answering with suitable meekness, released their wrath, quenched their madness and dissolved their impetuosity. For when they said, "We gave you strict orders not to teach in this name," the disciples, although they were able to work countless miracles, neither said nor did anything harsh but answered with all gentleness, saying, "Whether it is right to listen to you rather than to God, you must judge."”
Source
“"For we cannot but speak the things we have seen and heard:" so that we are witnesses who have a right to be believed. Already these as martyrs have borne testimony: set in the battle against all, they said, "We cannot but speak the things we have seen and heard." If the things we speak be false, reprehend them; if true, why hinderest thou? Such is philosophy! Those, in perplexity, these in gladness: those covered with exceeding shame, these doing all with boldness: those in fear, these in confidence.”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“For we cannot but speak,.... It was not physically, but morally impossible; or it was not lawful, and therefore they would not speak any other, and they could not avoid speaking, say they, the things which we have seen and heard; as the miracles and doctrines of Christ, his resurrection from the dead, of which they were eye and ear witnesses. This shows their great fidelity and integrity, their inviolable attachment to Christ, and their fearlessness of the displeasure and wrath of men.”
Source
1849
A.D.
1774–1849
“We have seen and heard. From these words, St. Chrysostom makes some important remarks on the conduct of Christians. On returning from the theatre, or any public meeting, each can relate what he has seen and heard. This is the fruit they reap from attending at public places of amusement; and would to God it were merely pleasure unmixed with poison. But on returning from Church, where they have been for instruction, they remember nothing, speak of nothing they have seen or heard. All is silence. Not even a thought is turned on what has been performed. (Hom. x. in Act.) — It is a curious fact, which the apologists for the innocence of modern plays would do well to attend to, that the theatre has always been avoided by the good and the virtuous of every age. When one of the ancient Fathers was exorcising a female demoniac, who had been possessed at the theatre, and bade the devil to depart; No, replied he, I had a right to take possession of her, for I found her in my own house. (Haydock)”
Source
1871
A.D.
1871
“For we cannot but speak the things which we have seen and heard--There is here a wonderful union of sober, respectful appeal to the better reason of their judges, and calm, deep determination to abide the consequences of a constrained testimony, which betokens a power above their own resting upon them, according to promise.”
Source

Undated

date unknown
date
unknown
Glossa Ordinaria Medieval
“For we cannot. That is, we will not, or it has been turned into nature (as with the angels who are confirmed) not to sin.”
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.