I will say unto God my rock - I will appeal to God as my defense, my helper, my Saviour. On the word rock, as applied to God, see the notes at Psalms 18:2.
Why hast thou forgotten me? - See the notes at Psalms 22:1. He had seemed to forget and forsake him, for He did not come to interpose and save him. This is a part of the prayer which he says Psalms 42:8 that he would use.
Why go I mourning? - On the meaning of the word used here - קדר qodēr - see Psalms 35:14, note; Psalms 38:6, note. The idea is that of being bowed down, made sad, deeply afflicted, as one forsaken.
Because of the oppression of the enemy - In the oppression of the enemy; that is, during its continuance, or on account of it. The word here rendered “oppression” means distress, affliction, straits, Job 36:15; 1 Kings 22:27; Isaiah 30:20. The “enemy” here referred to may have been Absalom, who had driven him from his throne and kingdom.