Jamieson, Fausset and Brown on John 14:15-17

15-17. If ye love me, keep my commandments. And I will pray the Father, &c.--This connection seems designed to teach that the proper temple for the indwelling Spirit of Jesus is a heart filled with that love to Him which lives actively for Him, and so this was the fitting preparation for the promised gift.

he shall give you another Comforter--a word used only by John; in his Gospel with reference to the Holy Spirit, in his First Epistle (1Jo 2:1), with reference to Christ Himself. Its proper sense is an "advocate," "patron," "helper." In this sense it is plainly meant of Christ (1Jo 2:1), and in this sense it comprehends all the comfort as well as aid of the Spirit's work. The Spirit is here promised as One who would supply Christ's own place in His absence.

that he may abide with you for ever--never go away, as Jesus was going to do in the body.