Manasseh was twelve years old when he began to reign
So that he was born three years after Hezekiah's recovery from his sickness, and in the seventeenth year of his reign:
and reigned fifty five years in Jerusalem:
among which must be reckoned the time of his captivity in Babylon; his reign was the longest of any of the kings of Judah: and his mother's name was Hephzibah; the name the church goes by, and signifies, "my delight or pleasure is in her", ( Isaiah 62:4 ) , no doubt she was a good woman, or Hezekiah would not have made choice of her for a wife; it is a tradition of the Jews F1, that she was the daughter of Isaiah, whose name, they say, is not mentioned, because so wicked a king was unworthy of such a grandfather.
F1 Hieron. Trad. Heb. in lib. Paralipom. fol. 86. F.