Joseph Benson's Commentary of the Old and New Testaments - Psalms 132:11-12
Psalms 132:11-12. The Lord has sworn in truth Not falsely or deceitfully, as men sometimes do, but sincerely and faithfully, what he will inviolably observe and fulfil, as the next clause expounds this. Of the fruit of thy body Of some of thy posterity, will I set upon thy throne See notes on 2 Samuel 7:12-16; and Psalms 89:3-4; Psalms 89:33, &c. If thy children will keep my covenant, &c. See notes on 1 Kings 8:25; 2 Chronicles 6:16. read more
Albert Barnes' Notes on the Whole Bible - Psalms 132:12
If thy children will keep my covenant ... - This was the condition implied in the promise - that they were to keep the law of God, and to serve and obey him. If they did not, they could not, of course, plead the promise. This principle is universal. We cannot plead any promise of God in our behalf, or in behalf of our children, unless we obey his commands, and are ourselves faithful to him. See the sentiment in this verse illustrated in the notes at Psalms 89:30-37. read more