John Calvin on John 13:28

28. Not one of those who were at table. Either John had not yet related to others what Christ had told him, or they were so much struck by it, that they lost their presence of mind; and, indeed, ill is probable, that John himself was almost out of his senses. But what then happened to the disciples, we frequently see: taking place in the Church, that few of the believers discern the hypocrites whom the Lord loudly condemns.