The Lord hear thee in the day of trouble. The people intercede for their king in a "clay of trouble" or "distress," when danger impends, and he is about to affront it. They are made to ask, first of all, that God will hear the king's prayers, which are no doubt being silently offered while they pray aloud.
The Name of the God of Jacob defend thee. (On the force of the expression, "the Name of God," see the comment upon Psalms 7:17.) "Jacob's God"—a favourite expression with David—is the God who made him the promise, "I will be with thee, and I will keep thee in all places whither thou goest" (Genesis 28:15).
"Defend thee" is scarcely a correct rendering. Translate, exalt thee.'