John Gill Commentary 2 Kings 24:18

"Zedekiah was twenty and one years old when he began to reign; and he reigned eleven years in Jerusalem: and his mother`s name was Hamutal the daughter of Jeremiah of Libnah." — 2 Kings 24:18 (ASV)

Ver. 18-20. Zedekiah was twenty years old when he began to reign , &c.] So that he was but between nine and ten years of age when his father Josiah died; for Jehoahaz reigned three months, Jehoiakim eleven years, and his son three months and ten days.

and he reigned eleven years in Jerusalem: and his mother's name was Hamutal the daughter of Jeremiah of Libnah ; by which it appears that he was the brother of Jehoahaz by father and mother's side, (2 Kings 23:31) . This and the two following verses are expressed in the same words as in (Jeremiah 52:1–3) , (See Gill on Jeremiah 52:1), (See Gill on Jeremiah 52:2), (See Gill on Jeremiah 52:3), in (2 Chronicles 36:10 2 Chronicles 36:13) , besides what is here said, is written, that he humbled not himself before Jeremiah the prophet of the Lord, that spoke in his name, but opposed him; and rebelling against the king of Babylon, broke his oath, and hardened his neck and heart against the Lord, and was obstinate, stubborn, and self-willed.