To the chief Musician, A Psalm of David. The LORD hear thee in the day of trouble; the name of the God of Jacob defend thee; The Lord hear thee - David had already offered the sacrifice and prayed. The people implore God to succor him in the day of trouble; of both personal and national danger.
The name of the God of Jacob - This refers to Jacob's wrestling with the Angel; Genesis 32:24 (note), etc. And who was this Angel? Evidently none other than the Angel of the Covenant, the Lord Jesus, in whom was the name of God, the fullness of the Godhead bodily. He was the God of Jacob, who blessed Jacob, and gave him a new name and a new nature. See the notes on the above place in Genesis.