Manasses was twelve years old when he began to reign, and he reigned five and fifty years in Jerusalem: the name of his mother was Haphsiba.

Manasseh was twelve years old when he began to reign; and he reigned five and fifty years in Jerusalem: and his mother's name was Hephzi-bah.

A son of twelve years is Manasseh in his reigning, and fifty and five years he hath reigned in Jerusalem, and the name of his mother is Hephzi-Bah;

Manasseh was twelve years old when he became king; for fifty-five years he was ruling in Jerusalem; and his mother's name was Hephzi-bah.

Manasseh was twelve years old when he had begun to reign, and he reigned for fifty-five years in Jerusalem. The name of his mother was Hephzibah.

Manasseh was twelve years old - Manasseh, therefore, was not born at the time of Hezekiah's dangerous illness; and it is probable that Hezekiah had at that time no son to succeed him. According to Josephus, this was the principal cause of his grief.
Hephzibah - Jewish tradition makes Hephzibah, Hezekiah's wife, the daughter of Isaiah; but this is scarcely probable. She was, however, no doubt, known to the prophet, and it may well have been in special compliment to her that Isaiah introduced her name Isaiah 62:4 as one that Jerusalem would bear after her restoration to God's favor. The name means, "My delight (is) in her."

Manasseh was twelve years old - He was born about three years after his father's miraculous cure; he was carried captive to Babylon, repented, was restored to his kingdom, put down idolatry, and died at the age of sixty-seven years. See 2-Chronicles 33:1-20.

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 (a), 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.
(a) Hieron. Trad. Hebrews. in lib. Paralipom. fol. 86. F.

Young persons generally desire to become their own masters, and to have early possession of riches and power. But this, for the most part, ruins their future comfort, and causes mischief to others. It is much happier when young persons are sheltered under the care of parents or guardians, till age gives experience and discretion. Though such young persons are less indulged, they will afterwards be thankful. Manasseh wrought much wickedness in the sight of the Lord, as if on purpose to provoke him to anger; he did more evil than the nations whom the Lord destroyed. Manasseh went on from bad to worse, till carried captive to Babylon. The people were ready to comply with his wishes, to obtain his favour and because it suited their depraved inclinations. In the reformation of large bodies, numbers are mere time-servers, and in temptation fall away.

MANASSEH'S WICKED REIGN, AND GREAT IDOLATRY. (2Ki. 21:1-18)
Manasseh was twelve years old when he began to reign--He must have been born three years after his father's recovery; and his minority, spent under the influence of guardians who were hostile to the religious principles and reforming policy of his father, may account in part for the anti-theocratic principles of his reign. The work of religious reformation which Hezekiah had zealously carried on was but partially accomplished. There was little appearance of its influence on the heart and manners of the people at large. On the contrary, the true fear of God had vanished from the mass of the people; corruption and vice increased, and were openly practised (Isaiah 28:7, &c.) by the degenerate leaders, who, having got the young prince Manasseh into their power, directed his education, trained him up in their views, and seduced him into the open patronage of idolatry. Hence, when he became sovereign, he introduced the worship of idols, the restoration of high places, and the erection of altars or pillars to Baal, and the placing, in the temple of God itself, a graven image of Asherah, the sacred or symbolic tree, which represented "all the host of heaven." This was not idolatry, but pure star-worship, of Chaldaic and Assyrian origin [KEIL]. The sun, as among the Persians, had chariots and horses consecrated to it (2-Kings 23:11); and incense was offered to the stars on the housetops (2-Kings 23:12; 2-Chronicles 33:5; Jeremiah 19:13; Zephaniah 1:5), and in the temple area with the face turned toward the sunrise (Ezekiel 8:16).

Reign of Manasseh (cf. 2 Chron 33:1-20). - 2-Kings 21:1. Manasseh was twelve years old when he began to reign, so that he was not born till after Hezekiah's dangerous illness (2-Kings 20:1.).

Reigned - In which time the years of his imprisonment are comprehended.