He prayed to him, and God let himself be entreated; he heard his plea and brought him back to Jerusalem, to his kingdom. Then Manasseh knew that Yahweh is God.
In context
11So Yahweh brought against them the army commanders of the king of Assyria. They caught Manasseh with hooks, bound him in bronze shackles and marched him off to Babylon. 12In his distress he sought the favour of Yahweh his God and humbled himself deeply before the God of his ancestors. 13He prayed to him, and God let himself be entreated; he heard his plea and brought him back to Jerusalem, to his kingdom. Then Manasseh knew that Yahweh is God. 14After this he built an outer wall for the City of David, west of Gihon in the valley, reaching the entrance of the Fish Gate and circling the Ophel, and he raised it to a great height. He also posted army commanders in every fortified city of Judah. 15He cleared the foreign gods and the idol out of the house of Yahweh, along with all the altars he had built on the mount of the house of Yahweh and in Jerusalem, and he dumped them outside the city.