John 16:28

I came forth from the Father
This is the sum of what the apostle believed, and Christ, in these discourses of his, had been speaking of. This his coming forth from the Father is to be understood, not of his eternal filiation; nor of his coming forth in a way of grace towards his own people in the council and covenant of grace and peace; nor of his constitution, as Mediator, from everlasting; but of his coming in the flesh in the fulness of time: which supposes that he was, that he existed as a divine person before; that he was with the Father before; that he came forth from him with his knowledge, mind, and will; he came not of himself, but he sent him; and yet he came willingly, was not forced, or did not come against his will: and this does not suppose any local motion, or change of place, but only intends an assumption of the human nature into unity with his divine person, who fills heaven and earth with his presence; nor any separation from his Father, with whom he was, and in whose bosom he lay when he was made flesh, and dwelt among men; nor any absence from heaven, for he was there when on earth.

And am come into the world;
where he was before, as the Creator and upholder of it, by his immensity and powerful presence; this designs his coming and manifestation in the flesh, which in general was to do the whole will of God, which he in council and covenant agreed to do, and for which he came down from heaven; and in particular to preach the Gospel, call sinners to repentance, give life and light to many, and to fulfil the law, by obeying its precepts, and bearing its penalty, and both to do and suffer in the room and stead of his people, and to save lost sinners, even the chief of them.

Again, I leave the world;
not that he relinquished the sustaining and government of it, as God, nor the care of his people in it, as Mediator, for whom he retains the same love as ever, and will not leave them fatherless and comfortless; nor was he leaving it as never to return more; for he will descend, in like manner he ascended, and will come a second time and judge the world in righteousness: but he was about to depart from it by death, having done the work and business for which he came about.

And go to the Father;
to give an account of his work unto him, as his righteous servant, being faithful to him that had appointed him; and to transact the affairs of his people; to appear in the presence of God for them; to present their petitions, be their advocate, make intercession for them, take possession of heaven in their name, and prepare it for them; to take his place at the right hand of God in human nature, and to be glorified with the glory promised him before the world was.