With whom my hand shall be established: my arm also shall strengthen him.
All Commentaries on Psalms 89:21 Go To Psalms 89
Augustine of Hippo
AD 430
21. "My hand shall hold Him fast, and My arm shall strengthen Him" (ver. 21): because there was a taking up of man; because flesh was assumed in the Virgin's womb, because by Him who in the form of God is coequal with the Father, the form of a servant was taken, and He became obedient unto death, even the death of the Cross.