What is the origin of repentance?

Repentance ultimately derives via Old French from Latin paenitēre “to regret, be sorry.” Other derivatives of paenitēre include penance, penitence, and penitentiary. Although paenitēre is of uncertain origin, it was frequently confused with the similar-sounding noun poena “punishment, penalty,” a borrowing from Ancient Greek poinḗ. Poena is the source of numerous words related to crime and its consequences, such as subpoena, penalty, punish, punitive, and even pain; while these words are likely unrelated to repentance, they all share a p-vowel-n root and refer to the aftermath of a mistake or unfortunate choice. Repentance first appeared in English in the early 1300s.