In our chronological journey through the Bible, we have placed most of the Psalms in David’s reign. The only ones we have not placed there are the ones we know are not David’s. But there are some Psalms regarded as Davidic we are unsure David wrote. Psalm 132 is one of them.
The Psalm sounds like it was written by one of David’s successors. It fundamentally calls God to do what God promised to do because of what David has done. David swore to build a dwelling place for God, a resting place where God’s priests would be clothed with righteousness.
David did that (rather Solomon did, but David got the credit for it).
In return, God promised to make Jerusalem His home, his dwelling and resting place. He promised to clothe his priests with salvation and David’s enemies with shame. He promised to make David’s reputation (horn) grow.
Do you see the similarities between the promises?
The Psalmist wants God to fulfill His promises to David, simply because He promised.
It may sound like an unfair expectation (kinda like a parent making a promise and then reneging because the circumstance changed), but it is his expectation none-the-less. That’s the nature of the promise of God: so sure and certain, so binding, that God’s people can have the confidence to bring it up to God when they think He’s let them down.