Our Lord having said, A little while, and the world seeth Me no more: but ye shall see Me: Judas, not the traitor named Scariot, but he whose Epistle is read among the Canonical Scriptures, asks His meaning: Judas saith unto Him, not Iscariot, Lord, how is it that Thou wilt manifest Thyself unto us, and not unto the world? Our Lord in reply explains why He manifests Himself to His own, and not to aliens, viz. because the one love Him, the other do not. Jesus answered and said unto him, If a man love Me, he will keep My words.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Tract. lxxvi. 1