This means that David would allow those people to be around him and live with him. Alternate translation: "I will allow the faithful of the land to live with me" (See: [[rc://en/ta/man/translate/figs-idiom]])
Here David speaks about "living" as if it were "walking." Alternate translation: "live in a way that is honest and right" or "live lives full of integrity" (See: [[rc://en/ta/man/translate/figs-metaphor]])