Ps 120:5

“Let us now come to this verse of the Psalm: "The Lord is thy defence upon the hand of thy right hand" [Psalm 121:5]. By hand he meaneth power. How do we prove this? Because the power of God also is styled the hand of God...Whereof John saith, "He gave unto them power to become the sons of God." [John 1:12] Whence hast thou received this power? "To them," he saith, "that believe in His Name." If then thou believest, this very power is given thee, to be among the sons of God. But to be among the sons of God, is to belong to the right hand. Thy faith therefore is the hand of thy right hand: that is, the power that is given thee, to be among the sons of God, is the hand of thy right hand...”