In my name — For my sake, in my room, and as my agent. He will teach you all things — Necessary for you to know. Here is a clear promise to the apostles, and their successors in the faith, that the Holy Ghost will teach them all that truth which is needful for their salvation.
Related Commentaries of John 14:26
John 14:26
26 But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.