But my faithfulness and my mercy shall be with him
The "faithfulness" of God was and is with Christ, in performing promises made to him respecting his work, and strength to do it, as man, and the glory that should follow; and also those made to his people in him, relating to grace here, and happiness hereafter: and though there was no "mercy" shown to Christ, as the surety of his people, but he was dealt with in strict justice; yet, as Mediator of the covenant, the special mercy of God is with him, even every blessing of it, called "the sure mercies of David"; and is only communicated through him; he is the mercy seat, from whence mercy is dispensed, and the propitiation through whom God is merciful to men; the words may be rendered, "my truth and my grace" F5, as they are by the Targum; and both are with Christ, the truth of doctrine, and all the fulness of grace, justifying, sanctifying, pardoning, adopting, and persevering grace, ( John 1:14 John 1:17 ) ,
and in my name shall his horn be exalted,
or "his glory", as the Targum; his power and dominion, of which the horn is an emblem; and his glory is displayed in having the same name his Father has: his name is expressive of his nature, being, and perfections, the name Jehovah; and his name of title and office "King of Kings, and Lord of lords"; or his name the Word of God, as the Targum; who, as such, is the brightness of his Father's glory: or the sense is, that, by the power of God, he should be raised from the dead, and have glory given him, and be exalted at his right hand, and made Lord and Christ; or by means of the Gospel, which is the name of the Lord, ( John 17:6 John 17:8 ) , his kingdom and dominion should be spread in the world; see ( 1 Samuel 2:10 ) .
F5 (ydoxw ytnwmaw) "et veritas mea, et gratia mea", Cocceius, Gejerus, Michaelis.