Charles H. Spurgeon on Psalms 110:1

My Lord. It was a higher honour to have Christ for his son, than to be a king; yet David does not say that Christ is his son, but rejoices that Christ is his Lord, and he Christ's servant. But this joy has also been procured for it: see Lu 1:43; Joh 20:28 Php 3:3,8. They who regard the Messiah only as the son of David, regard the lesser part of the conception of him. A dominion to which David himself is subject, shows the heavenly majesty of the King, and the heavenly character of his kingdom. John Albert Bengel.