Adam Clarke on John 16:28

I came forth from the Father - With whom I existed from eternity in glory.

Am come into the world - By my incarnation.

I leave the world - By my death.

And go to the Father - By my ascension. These four words contain the whole economy of the Gospel of man's salvation, and a consummate abridgment of the Christian faith. This gave the disciples a key to the whole of our Lord's discourse; and especially to that part, Joh 16:16, that had so exceedingly embarrassed them, as appears by Joh 16:17, Joh 16:18.