John 17:26

And I have declared unto them thy name
Himself, his nature, his perfections, especially of grace and mercy, his mind and will, his Gospel; (See Gill on John 17:6). A very fit person Christ was to make this declaration, since he was with him from all eternity, and was in his bosom; the Father did all in him, and his name is in him; and he is the faithful witness; nor is anything of God to be known savingly, but in and through Christ; the apostles are here particularly meant, though the same is true with respect to all that are given to Christ, who are his children and brethren, to whom he also declares the name of God:

and will declare it;
more fully to them after his resurrection, during his forty days' stay with them, and upon his ascension, when he poured down his Spirit in such a plentiful and extraordinary manner upon them; and will declare it to others besides them in the Gentile world; and still more in the latter day glory, and to all believers more and more:

that the love wherewith thou hast loved me, may be in them;
that is, that a sense of that love with which God loves his Son, as Mediator, might be in them and abide in them, and which is the rather mentioned because they are loved by the Father with the same love, and share all the blessed consequences of it, the knowledge and sense of which they come at, through Christ's declaring his Father's name unto them; and which they will have a greater sense of, and will be swallowed up in it in heaven to all eternity:

and I in them;
dwelling in them, taking up his residence in them; not only by his Spirit and grace here, but by his glorious presence with them hereafter; when they shall be brought to his Father's house, behold his glory, and be for ever with him.