Unbelievable
It is unbelievable that the man who wrote Prov. 5:20–23 and 6:20–24 would multiply wives and concubines from heathen nations. Polygamy itself was bad enough (it had caused his father David no end of trouble), but to take wives from heathen lands was deliberate apostasy. See Deut. 7:1–14. What was the cause of this repeated sin? Solomon’s heart was not right with God (11:4). God wanted “integrity of heart” (9:4), which means a united heart single to the glory of God. But Solomon had a divided heart—he loved the world as he tried to serve God. What a tragedy that the man who built the temple to the one true God should begin to worship at heathen altars.
Wiersbe, Warren W. The Bible Exposition Commentary: New Testament, vol. 1. Colorado Springs, CO: Victor Books, 2003.