Isaiah 49:3

And said unto me
Both in the everlasting council, and when he made a covenant with him in eternity; when he found him and anointed him, and laid help on him; and also when he brought him, his first begotten, into the world, at his incarnation: thou art my servant;
of his choosing, appointing, calling, sending, bringing forth, and supporting; so he was as Mediator, especially in his estate of humiliation, when he appeared in the form of a servant, and came not to be ministered unto, but to minister, and give his life a ransom for many; thereby to obtain redemption, which was the great work and service he was appointed to; which he readily undertook, and willingly and cheerfully engaged in, and diligently and faithfully performed; to whom justly belong the characters of an obedient, diligent, prudent, and faithful servant; in answering which he showed his regard to his Father's will, his love to his people, and his great humility and condescension: O Israel;
a name of Christ, and which properly belongs to him, being the antitype of Jacob or Israel; the Head and representative of the whole Israel of God; who was of Israel according to the flesh, and an Israelite indeed in a spiritual sense, and was only sent to the lost sheep of the house of Israel. Israel is a name of the church, often given to it in this prophecy; Christ and his church, by virtue of the union between them, have the same names; as she is sometimes called by his names, Christ, and the Lord our righteousness, so he is here called by her name Israel, ( 1 Corinthians 12:12 ) ( Jeremiah 23:6 ) ( 33:16 ) : in whom I will be glorified;
this is Jehovah's end in all he does in nature or grace; and is what Christ had in view in working out our salvation; and all the divine perfections are glorified in it by him, the wisdom, power, faithfulness, holiness, justice, love, grace, and mercy of God. Some render the words actively, "in thee" or "in whom I will glory" ^F20; as his own Son, in whom he is well pleased, being the brightness of his glory, and the express image of his person; and in whom also all the seed of Israel glory, as well as are justified. Or, as others, Israel is he, of "whom by thee I will glory", or "glorify" ^F21; meaning, that it was the spiritual and mystical Israel, the church, whom he would save by his Son and servant, the Messiah, and bring to glory.