Charles Ellicott Commentary 1 Kings 11:1-8

"Now king Solomon loved many foreign women, together with the daughter of Pharaoh, women of the Moabites, Ammonites, Edomites, Sidonians, and Hittites; of the nations concerning which Jehovah said unto the children of Israel, Ye shall not go among them, neither shall they come among you; for surely they will turn away your heart after their gods: Solomon clave unto these in love. And he had seven hundred wives, princesses, and three hundred concubines; and his wives turned away his heart. For it came to pass, when Solomon was old, that his wives turned away his heart after other gods; and his heart was not perfect with Jehovah his God, as was the heart of David his father. For Solomon went after Ashtoreth the goddess of the Sidonians, and after Milcom the abomination of the Ammonites. And Solomon did that which was evil in the sight of Jehovah, and went not fully after Jehovah, as did David his father. Then did Solomon build a high place for Chemosh the abomination of Moab, in the mount that is before Jerusalem, and for Molech the abomination of the children of Ammon. And so did he for all his foreign wives, who burnt incense and sacrificed unto their gods." — 1 Kings 11:1-8 (ASV)

Solomon's falling away is distinctly traced to his polygamy, contracting numerous marriages with “strange women.” Polygamy is also attributed to David (see 2 Samuel 3:2–5; 2 Samuel 15:16), perhaps marking the characteristic temperament of voluptuousness which seduced him into his great sin. However, it was carried out by Solomon on a scale corresponding to the magnificence of his kingdom, and, in his case, probably had the political object of alliance with neighboring or tributary kings. We find it inherited by Rehoboam (2 Chronicles 11:18–21), and it probably became, in different degrees, the practice of succeeding kings. Until this time, while polygamy, as everywhere in the East, had existed to some degree in Israel from patriarchal times, it must nevertheless have been checked by the marriage regulations of the Law.

Nor had there yet been the royal magnificence and wealth, under which alone it attains full development. We have some traces of it in the households of some of the Judges: Gideon (Judges 8:30), Jair (Judges 10:4), Ibzan and Abdon (Judges 12:9; Judges 12:14). Now, however, in spite of the prohibition of the Law (Deuteronomy 17:17), it became a recognized element of royal self-indulgence—such as is described in Ecclesiastes 2:7-8, and is perhaps traceable even through the beauty of the Song of Solomon. In itself, even without any incidental consequences, it must necessarily be a demoralizing power, as sinning against the primeval ordinance of God, and robbing natural relations of their true purity and sacredness. But in actual fact, it sinned still more by involving forbidden marriages with idolatrous races, with the often-predicted effect of a decline into idolatry.