The LORD swore an oath to David,
a sure oath that he will not revoke:
"One of your own descendants
I will place on your throne..."
Psalm 132 is one in a section of psalms called "songs of ascents," songs the people sang while traveling to Jerusalem for the yearly festivals. It strikes me hard today, this image of God's people going up to Jerusalem singing about Jesus, and they didn't know it -- they didn't know God's whole plan to fulfill this promise to their legendary King David.
What would they have thought, if the full plan had been revealed to them? That you yourself, LORD, would enter the house of David to fulfill your promise?
I don't know what the people climbing to Jerusalem, singing this song, would have thought. I know it fills me, re-fills me, with wonder. Before Israel ever knew what you would do for them, they sang about it. And you went so much farther to keep your promise than any mere human person could ever guess.