Then Peter said unto them, Repent, and be baptized every one of you in the name of Jesus Christ for the remission of sins, and you shall receive the gift of the Holy Spirit.
All Commentaries on Acts 2:38 Go To Acts 2
Gregory The Dialogist
AD 604
Do penance:
For, being about to speak of baptism, he spoke first of the lamentations of penitence; that they should first bathe themselves in the water of their own affliction, and afterwards wash themselves in the Sacrament of Baptism. With what conscience, then, can those who neglect to weep for their past misdeeds live secure of pardon, when (Peter) himself believed that penitence must be added even to this Sacrament which chiefly extinguishes sins?