Send thee help from the sanctuary. "The sanctuary" here is undoubtedly the holy place which David had established on Mount Zion, and in which he had placed the ark of the covenant. God's help was always regarded as coming especially from the place where he had "set his Name."
In the original it is, "Send thy help"—the help thou needest and prayest for. And strengthen thee out of Zion; rather, support thee.