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. 4) For then may His words be said to abide in us, when we do what He has commanded, and love what He has promised. But when His words abide in the memory, and are not found in the life, the branch is not accounted to be in the vine, because it derives no life from its root. So far as we abide in the Saviour we cannot will any thing that is foreign to our salvation. We have one will, in so far as we are in Christ, another, in so far as we are in this world. And by reason of our abode in this world, it sometimes happens that we ask for that which is not expedient, through ignorance. But never, if we abide in Christ, will He grant it us, Who does not grant except what is expedient for us. And here we are directed to the prayer, Our Father. Let us adhere to the words and the meaning of this prayer in our petitions, and whatever we ask will be done for us.