7 He has next added the reason why He prays for His words to be heard: For strangers are risen up against Me and violent men have sought after My soul; they have not set God before their eyes. The Only-begotten Son of God, the Word of God and God the Word— although assuredly He could Himself do all things that the Father could, as He says: What things soever the Father does, the Son also does in like manner, while the name describing the divine nature which was His inseparably involved the inseparable possession of divine power—yet in order that He might present to us a perfect example of human humility, both prayed for and underwent all things that are the lot of man.
Sharing in our common weakness He prayed the Father to save Him, so that He might teach us that He was born man under all the conditions of man's infirmity. This is why He was hungry and thirsty, slept and was weary, shunned the assemblies of the ungodly, was sad and wept, suffered and died. And it was in order to make it clear that He was subject to all these conditions, not by His nature, but by assumption, that when He had undergone them all He rose again. Thus all His complaints in the Psalms spring from a mental state belonging to our nature. Nor must it cause surprise if we take the words of the Psalms in this sense, seeing that the Lord Himself testified, if we believe the Gospel, that the Psalms spiritually foretold His Passion.
Source: Homilies on the Psalms (New Advent)