Albert Barnes Commentary Psalms 132:2

"How he sware unto Jehovah, And vowed unto the Mighty One of Jacob:" — Psalms 132:2 (ASV)

How he swore to the Lord — The solemn oath which he took: that he would make this the first object, that he would give himself no rest until this was done, and that he would sacrifice his personal ease and comfort so that he might thereby honor God. This oath or purpose is not recorded in the history. The fair interpretation of this would be either:

1. that these words properly expressed what was in David's mind at the time—that is, his acts implied that this purpose was in his heart; or
2. that this vow was actually made by David, though not elsewhere recorded. Such a vow might have been made, and its remembrance preserved by tradition, or it might have been suggested to the author of the psalm by direct inspiration.

And vowed to the mighty God of Jacob — . The God whom Jacob worshipped, and who had revealed himself so remarkably to him as a God of might or power.