There is another scripture which proves that there was a federal transaction between the Father and the Son, from several expressions therein used, namely, in Isa. xlii. 1, 6. which is, beyond dispute, spoken concerning our Saviour; for it is applied to him in the New Testament, Matt. xi. 18-21. Herein God the Father calls him _his Servant_, as denoting that it was his will, or (to use that mode of speaking, which is generally applied to covenants between man and man) that he stipulated with him, to perform the work which he engaged in, as Mediator, to which he is said to be _called in righteousness_; and, with respect to his human nature, in which he performed it, he is styled _God’s elect_, as fore-ordained hereunto, and the person _in whom his soul delighteth_, as he is glorified by him in the faithful discharge thereof; and, that he might not fail therein, God promises _to hold his hand, and keep him_; and, as the result of his having accomplished it, _to give him for a covenant of the people, for a light of the Gentiles_.
And elsewhere, in Isa. xlix. 8, 9. which also appears to be spoken to Christ, not only from the context, but from the reference to it in the New Testament, 2 Cor. vi. 2. _In an acceptable time have I heard thee, and in a day of salvation have I helped thee; and I will preserve thee, and give thee for a covenant of the people, to establish the earth, to cause to inherit the desolate heritages; that thou mayest say to the prisoners, Go forth; to them that are in darkness, Shew yourselves_, we have a plain intimation of his being ordained by the Father to perform that work, which he was engaged in, as Mediator; and his _being given for a covenant of the people_, signifies his being sent into the world, in pursuance of a covenant, in which the salvation of his people was contained. And there is another scripture, in which our Saviour, speaking to his disciples, says, in Luke xxii. 29. _I appoint unto you a kingdom, as my Father hath appointed me_;[94] or, I confer the blessings of this kingdom upon you, in a covenant way, as my Father hath appointed me to do, in that eternal covenant, which passed between him and me.
Again, there are several rewards, which were promised to him, as the consequence of his discharging the work committed to him, some of which respected that glory which belongs to his person, as Mediator; and others, more especially, respected the salvation of his people, and therein the success of his undertaking: thus it is said, in Isa. liii. 10. _When thou shalt make his soul an offering for sin, he shall see his seed; he shall prolong his days, and the pleasure of the Lord shall prosper in his hands_; together with several other things relating to the event, and consequence of his performing the work he was engaged in.