Psalms 89:21

“With whom my hand shall be established, etc.] A promise of God’s gracious presence with Christ, as man and Mediator, which is his work; of a communication of grace and strength from him, to carry him through it; and of his supporting and upholding him under it; which hand of his power and grace would be always prepared and ready for him, as the word f1271 signifies, and stable and firm with him, so that he should have success in it; the pleasure of the Lord should prosper in his hand; so the Targum, ''for my hands are prepared for his help;” the Septuagint, Vulgate Latin, and all the eastern versions, “mine hand shall help him”; and which is confirmed in the next words: mine arm also shall…”

“With whom my hand shall be established - Septuagint: “My hand shall aid him.” Luther; “My hand shall hold him.” DeWette; “With him my hand shall be continually.” Professor Alexander; “Shall ever be present.” The idea is, that God would always defend or protect him. He would not merely interpose at times, or at intervals, but he would be his constant protector. His hand would be permanently, or constantly, extended for his aid - as if it were a part of David’s own person, or were his own hand, to be used as he pleased. So God is the constant helper of his people. They may rely on his power; they may avail themselves of it, as if it were their own. Mine arm also shall strengthen him - In using…”

“With: Psa 18:32-39, Psa 80:15-17; Sa2 7:8-16; Isa 42:1, Isa 49:8 mine: Psa 89:13; Isa 41:10; Eze 30:24, Eze 30:25; Zac 10:12 Psalms 89:22”