Bible (KJV) Apocrypha/Deuterocanon: Prayer of Manasseh
The Prayer of Manasseh is a short work of only 15 verses that purports to be the penitential prayer of the Judean king Manasseh, who is recorded in the Bible as one of the most idolatrous (2 Kings 21:1-18). However, after having been taken captive by the Assyrians, he prays for mercy (2 Chronicles 33:10-17) and turns from his idolatrous ways. (Summary by Wikipedia)