Augustine of Hippo
Catena Aurea · Johannesevangelium 13
When Jesus had thus said, he was troubled in spirit, and testified, and said, Verily, verily, I say unto you, that one of you shall betray me. Then the disciples looked one on another, doubting of whom he spake. Now there was leaning on Jesus’ bosom one of his disciples, whom Jesus loved. Simon Peter therefore beckoned to him, that he should ask who it should be of whom he spake. He then lying on Jesus’ breast saith unto him, Lord, who is it? Jesus answered, He it is, to whom I shall give a sop, when I have dipped it. And when he had dipped the sop, he gave it to Judas Iscariot, the son of Simon. And after the sop Satan entered into him. Then said Jesus unto him, That thou doest, do quickly. Now no man at the table knew for what intent he spake this unto him. For some of them thought, because Judas had the bag, that Jesus had said unto him, Buy those things that we have need of against the feast; or, that he should give something to the poor. He then having received the sop went immediately out: and it was night. He then lying on Jesus’ breast, saith unto Him, Lord, who is it?
(Tr. lxii) But some will say, was his being given up to the devil the effect of his receiving the sop from Christ? To whom we answer, that they may learn here the danger of receiving amiss what is in itself good. If he is reproved who does not discern, i. e. who does not distinguish, the Lord’s body from other food, how is he condemned who, feigning himself a friend, comes an enemy to the Lord’s table?