Charles Ellicott Commentary 2 Chronicles 36:13

"And he also rebelled against king Nebuchadnezzar, who had made him swear by God: but he stiffened his neck, and hardened his heart against turning unto Jehovah, the God of Israel." — 2 Chronicles 36:13 (ASV)

And he also rebelled. — 2 Kings 24:20.

Who had made him swear by God. — When Nebuchadnezzar appointed Zedekiah vassal-king of Judah, he would naturally make him swear fealty to himself by the God of his fathers. The fact is not specially recorded in Kings; but the prophet Ezekiel makes it the point of a prophecy against the king and his nobles (Ezekiel 17:11–21; compare especially 2 Chronicles 36:17, mine oath that he hath despised.)

But (and) stiffened his neck and hardened his heart. — (Compare a similar expression in Deuteronomy 2:30; 2 Kings 17:14; Jeremiah 19:15.) Zedekiah was not personally unfavourable to the prophet Jeremiah, and consulted him more than once; but he was too weak and timid to stand by the prophetic counsel, in defiance of his nobles who were intriguing with Egypt.