Augustine of Hippo
Catena Aurea · Matthäusevangelium 26
And he went a little farther, and fell on his face, and prayed, saying, O my Father, if it be possible, let this cup pass from me: nevertheless not as I will, but as thou wilt. And he cometh unto the disciples, and findeth them asleep, and saith unto Peter, What, could ye not watch with me one hour? Watch and pray, that ye enter not into temptation: the spirit indeed is willing, but the flesh is weak. He went away again the second time, and prayed, saying, O my Father, if this cup may not pass away from me, except I drink it, thy will be done. And he came and found them asleep again: for their eyes were heavy. And he left them, and went away again, and prayed the third time, saying the same words.
(de Cons. Ev. iii. 4.) And that none might think that He limited His Father’s power, He said not, If thou canst do it, but If it may be, or, If it be possible; as much as to say, If thou wilt. For whatever God wills can be done, as Luke expresses more plainly; for he says not, If it be possible, but If thou wilt.