The interpretation timeline
Acts 7:55 Douay-Rheims

But he, being full of the Holy Ghost, looking up steadfastly to heaven, saw the glory of God, and Jesus standing on the right hand of God. And he said: Behold, I see the heavens opened, and the Son of man standing on the right hand of God.

A.D. 220 – 1871 7 witnesses 8 excerpts

Patristic

before A.D. 750
220
A.D.
Tertullian Patristic
c. A.D. 150–220
“He is seen by Stephen, at his martyrdom by stoning, still sitting at the right hand of God [Acts 7:55] where He will continue to sit, until the Father shall make His enemies His footstool. [Hebrews 10:12-13] He will come again on the clouds of heaven, just as He appeared when He ascended into heaven. [Acts 1:11]”
“"He sitteth at the Father's right hand " -not the Father at His own. He is seen by Stephen, at his martyrdom by stoning, still sitting at the right hand of God where He will continue to sit, until the Father shall make His enemies His footstool.”
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“He mentions the cause of his angelic appearance: "But he, being full of the Holy Ghost, looked up steadfastly into heaven, and saw the glory of God, and Jesus standing on the right hand of God." And in this manner He appeared to him: that, were it but so, the Jews might receive Him: for since the idea of His sitting at the right hand of God was offensive to them, for the present he brings forward only what relates to His Resurrection. This is the reason also why his face was glorified. For God, being merciful, desired to make their machinations the means of recalling them unto Himself. And when he said, "I see the heavens opened, they stopped their ears, and ran upon him with one accord." And yet in what respect are these things deserving of accusation? "Upon him," the man who has wrought such miracles, the man who has prevailed over all in speech, the man who can hold such discourse! As if they had got the very thing they wanted, they straightway give full scope to their rage.”
Source

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Then they cried out with a loud voice,.... These were not the sanhedrim, but the common people; the Ethiopic version reads, "the Jews cried out"; which, they did, in a very clamorous way, either through rage and madness, or in a show of zeal against blasphemy; and cried out, either to God to avenge the blasphemy, or rather to the sanhedrim to pass a sentence on him, or, it may be, to excite one another to rise up at once, and kill him, as they did: and stopped their ears; with their fingers, pretending they could not bear the blasphemy that was uttered. This was their usual method; hence they say, (o). "if a man hears anything that is indecent, (or not fit to be heard,) let him put his fingers in his ears hence the whole ear is hard, and the tip of it soft, that when he hears anything that is not becoming, he may bend the tip of the ear within it.'' By either of these ways these men might stop their ears; either by putting in their fingers, or by turning the tip of the ear inward. And ran upon him with one accord; without any leave of the sanhedrim, or waiting for their determination, in the manner the zealots did; See Gill on Mat 10:4, Joh 16:2. (o) T. Bab. Cetubot, fol. 5. 1. 2.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“Saw the glory of God - The Shekinah, the splendor or manifestation of the Divine Majesty. And Jesus standing on the right hand of God - In his official character, as Mediator between God and man. Stephen had this revelation while in the Sanhedrin; for as yet he had not been forced out of the city. See Act 7:58.”
1849
A.D.
1774–1849
“This is the comfort of all martyrs. (Bristow) — This the support of every Christian under the severest trials of either mind or body: this the sweetener of every burthen and cross.”
1871
A.D.
1871
“But he, being full of the Holy Ghost, looked up steadfastly into heaven, and saw the glory of God--You who can transfer to canvas such scenes as these, in which the rage of hell grins horribly from men, as they sit condemned by a frail prisoner of their own, and see heaven beaming from his countenance and opening full upon his view--I envy you, for I find no words to paint what, in the majesty of the divine text, is here so simply told. "But how could Stephen, in the council-chamber, see heaven at all? I suppose this question never occurred but to critics of narrow soul, one of whom [MEYER] conjectures that he saw it through the window! and another, of better mould, that the scene lay in one of the courts of the temple" [ALFORD]. As the sight was witnessed by Stephen alone, the opened heavens are to be viewed as revealed to his bright beaming spirit. and Jesus standing on the right hand of God--Why "standing," and not sitting, the posture in which the glorified Saviour is elsewhere represented? Clearly, to express the eager interest with which He watched from the skies the scene in that council chamber, and the full tide of His Spirit which He was at that moment engaged in pouring into the heart of His heroical witness, till it beamed in radiance from his very countenance.”
Source

Undated

date unknown
date
unknown
Glossa Ordinaria Medieval
“Standing. Immovably, because not about to fall again; or the posture is indicated of one helping, and of one judging injuries, and of one fighting for his servant. I see the heavens. About to depart from the earth, he saw the heavens opened, that he who despised earthly life for Christ might merit the inheritance of heaven, and therefore in his very passion he sees the reward. The Son of man. Although Christ is the Son of God, yet he preferred to call him the Son of man, that the unbelief of the Jews might be confounded, who crucified him as a mere man, whom they refused to believe to be God.”
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.