Isaiah 55:4

“Behold, I have given him for a witness to the people, &c.] That is, the Messiah, as Aben Ezra, Kimchi, and Ben Melech rightly interpret it. This respects an act past in eternity, in God’s eternal purposes and decrees, when he appointed Christ to the office of a Mediator; and this was an act of his grace, a free gift of his, flowing from his love to his people, both Jews and Gentiles, even all his elect, to whom Christ is a “witness”, both of his father and of himself: of his father, of his good will to men, in forming the scheme of their salvation; of his love to sinners, in the mission of him; of his justice and holiness, which appear in his being the propitiation for sin; of his truth in…”

“him--the mystical David (Eze 37:24-25; Jer 30:9; Hos 3:5). Given by God (Isa 49:6). witness--He bore witness even unto death for God, to His law, claims, and plan of redeeming love (Joh 18:37; Rev 1:5). Revelation is a "testimony"; because it is propounded to be received on the authority of the Giver, and not merely because it can be proved by arguments. commander--"preceptor" [HORSLEY]; "lawgiver" [BARNES]. to the people--rather, "peoples."”

“Behold, I have given him - This is evidently the language of God respecting the Messiah, or of David as representing the Messiah. Rosenmuller supposes that the name David here is used to designate the Messiah, and in support of this appeals to Ezekiel 34:23-24; Ezekiel 37:24-25; Jeremiah 30:9; Hosea 3:5. An examination of these passages will show that they all refer to the Messiah by the name of David; and it is morally certain that in the passage before us, the name David Isaiah 55:3 suggested the Messiah. It seems to me that this is to be regarded as a direct address respecting the Messiah, and that the object of the speaker here is to state a reason why he should be embraced. That reason…”

“Behold - I have appointed, and will in due time actually give. Him - The David last mentioned, even Christ. A witness - To declare the will of God concerning the duty and salvation of men, to bear witness to truth, to confirm God's promises, and, among others, those which respect the calling of the Gentiles: to be a witness of both parties of that covenant made between God and men. The people - To all people. Isaiah 55:5”

“I have: Joh 3:16, Joh 18:37; Ti1 6:13; Rev 1:5, Rev 3:14 a leader: Isa 49:8-10; Psa 2:6; Jer 30:9; Eze 34:23, Eze 34:24; Dan 9:25; Hos 3:5; Mic 5:2-4; Mat 2:6, Mat 28:18-20; Joh 10:3, Joh 10:27, Joh 12:26, Joh 13:13; Th2 1:8; Eph 5:24; Heb 2:10, Heb 5:9 Isaiah 55:5”