Luke
Acts 3:19ESV·traditional attribution

Repent therefore, and turn back, that your sins may be blotted out,

John Calvin Reformed @genevareformer

19. Repent We must note, that when he exhorteth unto repentance, he doth also declare that there is remission of sins prepared for them before the face of God. For, as I said of late, no man can be stirred up to repentance, unless he have salvation set before him; but he which doth despair of pardon, being, as it were, given over unto destruction...

Matthew Henry Presbyterian @wholebiblehenry

We have here the sermon which Peter preached after he had cured the lame man. When Peter saw it. 1. When he saw the people got together in a crowd, he took that opportunity to preach Christ to them, especially the temple being the place of their concourse, and Solomon's porch there: let them come and hear a more excellent wisdom than Solomon's, for, behold...

Commenting on Acts 3:12-26

John Gill Reformed Baptist @doctorgill

Repent ye therefore,.... The Ethiopic version adds, "and be baptized"; see Gill on Act 2:38, and be converted. The apostle's sense is, repent of the sin of crucifying Christ, which is what he had been charging them with, and turn unto him, and acknowledge him as the Messiah; receive his doctrines, and submit to his ordinances; externally reform in life and conversation, and bring forth...