Commenting on Acts 2:38, John Chrysostom wrote the following, showing that the doctrine of baptismal regeneration was part-and-parcel of patristic-era soteriology:
He does not yet say, Believe, but, Be baptized every one of you. For this they received in baptism. Then he speaks of the gain; For the remission of sins, and ye shall receive the gift of the Holy Ghost. If you are to receive a gift, if baptism conveys remission, why delay?
Source: S. John Chrysostom. (1851–1852). The Homilies of S. John Chrysostom Archbishop of Constantinople, on the Acts of the Apostles: Parts I & II, Hom. I–LV (pp. 97–98). Oxford; London: John Henry Parker; F. and J. Rivington.