“And he also rebelled against king Nebuchadnezzar, who had made him swear by God: but he stiffened his neck, and hardened his heart from turning unto the LORD God of Israel.”
King James Version (KJV)
36:13 By God - Who had required him to swear fealty and constant obedience to him by the true God, whom he called upon to be a witness against him if he broke his oath. So his rebellion was aggravated with perjury, and horrid contempt of God.