“And His name, through faith in His name, has made this man strong, whom you see and know: yea, the faith which is by Him has given him this perfect soundness in the presence of you all.” Seeking to declare the matter (ζητὥν τὸ πρἅγμα εὶπεἵν), he straightway brings forward the sign: “In the presence,” he says, “of you all.” As he had borne hard upon them, and had shown that He Whom they crucified had risen, again he relaxes, by giving them the power of repentance; “And now, brethren, I know that through ignorance you did it, as did also your rulers.” This is one ground of excuse.
The second is of a different kind. As Joseph speaks to his brethren, God did send me before you; what in the former speech he had briefly said, in the words, “Him, being delivered by the determinate counsel and foreknowledge of God, you have taken,”— this he here enlarges upon: “But what God before had showed by the mouth of all His Prophets, that His Christ should suffer, He has so fulfilled.” At the same time showing, that it was not of their doing, if this be proved, that it took place after God's counsel.
He alludes to those words with which they had reviled Him on the Cross, namely “Let Him deliver Him, if He will have Him; for He said, I am the Son of God. If He trust in God, let Him now come down from the cross.” O foolish men, were these idle words? It must needs so come to pass, and the prophets bear witness thereunto. Therefore if He descended not, it was for no weakness of His own that He did not come down, but for very power. And Peter puts this by way of apology for the Jews, hoping that they may also close with what he says.
“He has so fulfilled,” he says. Do you see now how he refers everything to that source? “Repent ye therefore,” he says, “and be converted.” He does not add, “from your sins;” but, “that your sins, may be blotted out,” means the same thing. And then he adds the gain: “So shall the times of refreshing come from the presence of the Lord.” This betokens them in a sad state, brought low by many wars. For it is to the case of one on fire, and craving comfort, that the expression applies.
And see now how he advances. In his first sermon, he but slightly hinted at the resurrection, and Christ's sitting in heaven; but here he also speaks of His visible advent. And He shall send Jesus the Christ ordained (for you), “Whom the heaven must (i.e. must of necessity) receive, until the times of the restitution of all things.” The reason why He does not now come is clear. “Which God has spoken,” he continues, “by the mouth of His holy prophets since the world began.
For Moses truly said unto the fathers, A Prophet shall the Lord your God raise up unto you of your brethren, like me; him shall you hear in all things whatsoever he shall say unto you.” Before, he had spoken of David, here he speaks of Moses. “Of all things,” he says, “which He has spoken.” But he does not say, “which Christ,” but, “which God has spoken by the mouth of all His holy prophets since the world began.” (<!--<span class="stiki"></span>-->v. 20-21.) Then he betakes him to the ground of credibility, saying, “A Prophet shall the Lord your God raise up unto you of your brethren, like me; Him shall you hear in all things.”
And then the greatness of the punishment: “And it shall come to pass, that every soul which will not hear that Prophet, shall be destroyed from among the people. Yea, and all the prophets, from Samuel and those that follow, after, as many as have spoken have likewise foretold of these days.” (<!--<span class="stiki"></span>-->v. 23-24.) He has done well to set the distinction here. For whenever he says anything great, he appeals to them of old. And he found a text which contained both truths; just as in the other discourse he said, “Until He put His foes under His feet.” The remarkable circumstance is, that the two things stand together; that is, subjection and disobedience, and the punishment.
“Like unto me,” he says. Then why are you alarmed? “You are the children of the prophets”: so that to you they spoke, and for your sakes have all these things come to pass. For as they deemed that through their outrage they had become alienated (and indeed there is no parity of reason, that He Who now is crucified, should now cherish them as His own), he proves to them that both the one and the other are in accordance with prophecy. “You are the children,” he says, “of the Prophets, and of the covenant which God made with our fathers, saying unto Abraham, 'And in your seed shall all the kindreds of the earth be blessed.'
Unto you first,” he continues, “God having raised up His Son (τόν Παἵδα) sent Him.” “To others indeed also, but to you first who crucified Him.” “To bless you,” he adds, “in turning away every one of you from his iniquities.”
Source: Homilies on Acts (New Advent)