This “Song of Ascent” deals with David’s pledge to build a temple to YHWH in Jerusalem, a promise unkept until son Solomon’s rule.
David is quoted as telling YAH he would not sleep until the temple was built as “Your resting place, / You and the ark of Your strength.”
Obviously an exaggeration, David doesn’t explain that when he went “to the comfort of [his] bed,” he wasn’t there to snooze, anyway.
Just ask Bathsheba, with whom David made whoopee and then had her old man killed. The king wasn’t thinking about sleep that day.
In turn, YHWH promised to prop up sinful King David and to ensure that “the fruit of [his] body … shall sit upon [his] throne forevermore.”
What really mystifies me, though, is how the Ark of the Covenant, which contained the laws of Israel, is presented as “[YAH’s] strength.”
How can something be a strength — like the Ten Commandments or like, say, our Constitution — if a weak man is greater than the law?