Midrash sobre Sanhedrin 3:14

Rabbi Joshua said: Know thou the power of repentance. Come and see from Manasseh, son of Hezekiah, who perpetrated all the evil abominations much more than all the nations. He made his son to pass through the fire to Baal outside Jerusalem, causing (doves) to fly, and sacrificing to all the host of heaven. The princes of the troops of the king of Babylon came, and they caught him by the hair of his head, and brought him down to Babylon, and they put him in a pan (over) a fire, and there he called upon all the other gods to whom he had sacrificed, and not one of them either answered him or saved him. He said: I will call on the God of my fathers with all my heart; perhaps He will do unto me according to all His wonders which He did unto my father. And he called on the God of his fathers with all his heart, and He was entreated of him, and He heard his supplication, as it is said, "And he prayed unto him; and he was intreated of him, and heard his supplication… then Manasseh knew that the Lord he was God" (2 Chron. 33:18). In that hour Manasseh said: There is both judgment as well as a judge.