And when he was in affliction, he besought the LORD his God, and humbled himself greatly before the God of his fathers,

Wesley's Notes

33:12 Besought - It becomes sinners to humble themselves before that God, whom they have offended. It becomes sufferers to humble themselves before him that corrects them, and to accept of the punishment of their iniquity.

Jamieson-Fausset-Brown Bible Commentary

12, 13. when he was in affliction, he besought the Lord his God-In the solitude of exile or imprisonment, Manasseh had leisure for reflection. The calamities forced upon him a review of his past life, under a conviction that the miseries of his dethronement and captive condition were owing to his awful and unprecedented apostasy (2Ch 33:7) from the God of his fathers. He humbled himself, repented, and prayed for an opportunity of bringing forth the fruits of repentance. His prayer was heard; for his conqueror not only released him, but, after two years' exile, restored him, with honor and the full exercise of royal power, to a tributary and dependent kingdom. Some political motive, doubtless, prompted the Assyrian king to restore Manasseh, and that was most probably to have the kingdom of Judah as a barrier between Egypt and his Assyrian dominions. But God overruled this measure for higher purposes. Manasseh now showed himself, by the influence of sanctified affliction, a new and better man. He made a complete reversal of his former policy, by not only destroying all the idolatrous statues and altars he had formerly erected in Jerusalem, but displaying the most ardent zeal in restoring and encouraging the worship of God.

Matthew Henry's Concise Commentary

33:1-20 We have seen Manasseh's wickedness; here we have his repentance, and a memorable instance it is of the riches of God's pardoning mercy, and the power of his renewing grace. Deprived of his liberty, separated from his evil counsellors and companions, without any prospect but of ending his days in a wretched prison, Manasseh thought upon what had passed; he began to cry for mercy and deliverance. He confessed his sins, condemned himself, was humbled before God, loathing himself as a monster of impiety and wickedness. Yet he hoped to be pardoned through the abundant mercy of the Lord. Then Manasseh knew that Jehovah was God, able to deliver. He knew him as a God of salvation; he learned to fear, trust in, love, and obey him. From this time he bore a new character, and walked in newness of life. Who can tell what tortures of conscience, what pangs of grief, what fears of wrath, what agonizing remorse he endured, when he looked back on his many years of apostacy and rebellion against God; on his having led thousands into sin and perdition; and on his blood-guiltiness in the persecution of a number of God's children? And who can complain that the way of heaven is blocked up, when he sees such a sinner enter? Say the worst against thyself, here is one as bad who finds the way to repentance. Deny not to thyself that which God hath not denied to thee; it is not thy sin, but thy impenitence, that bars heaven against thee.