John Calvin Commentary Psalms 132:11

"Jehovah hath sworn unto David in truth; He will not turn from it: Of the fruit of thy body will I set upon thy throne." — Psalms 132:11 (ASV)

Jehovah sware unto David. Here he brings out the idea still more clearly, that the only thing he regarded in David was the free promise which God had made to him. He notes the fact, as confirming his faith, that God had ratified the promise by oath.

As to the particular words used, he speaks of God having sworn in truth, that is, not fallaciously, but in good faith, so that no doubt could be entertained that he would depart from his word. The thing promised was a successor to David of his own seed; for though he did not lack children, he had already almost despaired of the regular succession, due to the fatal confusions that prevailed in his family, and the discord that internally tore apart his household and might eventually ruin it.

Solomon was particularly marked out, but the promise extended to a continuous line of successors. This arrangement affected the welfare of the whole Church, and not of David only, and the people of God are encouraged by the assurance that the kingdom which he had established among them possessed a sacred and enduring stability. Both king and people needed to be reminded of this divine foundation upon which it rested.

We see how insolently the sovereigns of this world often conduct themselves—filled with pride, though in words they may acknowledge that they reign by the grace of God. How often, moreover, do they violently usurp the throne; how rarely do they come to it in a regular manner. A distinction is therefore drawn between the kingdoms of this world and that which David held by the sacred tenure of God’s own oracle.