Augustine of Hippo
Catena Aurea · Johannesevangelium 15
Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me. I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing. If a man abide not in me, he is cast forth as a branch, and is withered; and men gather them, and cast them into the fire, and they are burned. If ye abide in me, and my words abide in you, ye shall ask what ye will, and it shall be done unto you.
(Tract. lxxxi. 3) For the branches of the vine are as contemptible, if they abide not in the vine, as they are glorious, if they abide. One of the two the branch must be in, either the vine, or the fire: if it is not in the vine, it will be in the fire.