Albert Barnes Commentary Psalms 71:21

"Increase thou my greatness, And turn again and comfort me." — Psalms 71:21 (ASV)

Thou shalt increase my greatness — You will not merely restore me to my former condition, but will enlarge my happiness, and will do still greater things for me.

And comfort me on every side — literally, “You will turn yourself; You will comfort me.” The word also means to surround; to encompass (Genesis 2:11, Genesis 2:13; 1 Kings 7:24; Psalms 18:5); and the idea here may be that God would “go around him,” or encircle him, and would thus comfort him. This idea is expressed in our common version. It was the confident assurance of entire, or complete consolation.