2 Kings 18:2

Overview - 2 Kings 18
Hezekiah's good reign.
He destroys idolatry, and prospers.
The inhabitants of Samaria are carried captive for their sins.
13 Sennacherib invading Judah, is pacified by a tribute.
17 Rab-shakeh, by blasphemous persuasions, solicits the people to revolt.
Treasury of Scripture Knowledge

2 Kings 18:2  (King James Version)
Twenty and five years old was he when he began to reign; and he reigned twenty and nine years in Jerusalem. His mother's name also was Abi, the daughter of Zachariah.

Twenty and five years old
As Ahaz was 20 years old when he began to reign, and died when he had reigned 16 years, his whole age only amounted to 36 years; and as Hezekiah was, at least, entering on his 25th year when he began to reign, then Ahaz must have been under 12 years of age when his son was born! This is not at all impossible: and there are well-attested facts of men having children at as early a period, especially in eastern countries.

M. 3278-3306. B.C. 726-698. Abi.
2 Chronicles 29:1