All the people that were left of the Amorites Who, it is likely, by this time were become proselytes to the Jewish religion, as the Gibeonites were, or at least renounced their idolatry. Upon those did Solomon levy a tribute He used them as bond-men, and imposed bodily labours upon them. “But why did not Solomon destroy them, as God had commanded, when now it was fully in his power to do so?” The command to destroy them, (Deuteronomy 7:2,) did chiefly, if not only, concern that generation of Canaanites who lived in or near the time of the Israelites entering into Canaan. And that command seems not to have been absolute, but conditional, and with some exception for those who should submit and embrace the true religion, as may be gathered both from Joshua 11:19, and from the history of the Gibeonites. For if God's command had been absolute, the oaths of Joshua, and of the princes, could not have obliged them, nor dispensed with such a command.
Related Commentaries of 1 Kings 9:20
1 Kings 9:20-21
20 And all the people that were left of the Amorites, Hittites, Perizzites, Hivites, and Jebusites, which were not of the children of Israel,
21 Their children that were left after them in the land, whom the children of Israel also were not able utterly to destroy, upon those did Solomon levy a tribute of bondservice unto this day.