Albert Barnes Commentary Psalms 71:6

"By thee have I been holden up from the womb; Thou art he that took me out of my mother`s bowels: My praise shall be continually of thee." — Psalms 71:6 (ASV)

By thee have I been holden up from the womb—From the beginning of my existence. The “idea” in all this is that since God had sustained him from his earliest years—since he had shown his power in keeping him and manifested his care for him—there was ground to pray that God would keep him still, and that he would guard him as old age came on. The sentiment in this verse is substantially the same as in (Psalms 22:9–10). See the notes at that passage.

My praise shall be continually of thee—My praise shall ascend to you constantly. I will not cease to praise you. Compare the notes at (Psalms 22:25).