John 13:2

supper being ended There are two readings here, but neither of them means -being ended," moreover the supper is not ended (John 13:26). The common reading would mean -supper having begun," and the better reading, -when supper was at hand," or, -when supper was beginning." "It was the custom for slaves to wash the feet of the guests before sitting down to meat; and we are tempted to suppose that the symbolical act, which our Evangelist relates here, took the place of this custom." S. p. 214.

the devil … to betray him The true reading gives us, The devil having now put it into the heart, that Judas, Simon's son, Iscariot, should betray Him. Whose heart? Only two answers are possible grammatically; (1) the heart of Judas, (2) the devil's own heart. The latter is incredible, if only for the reason that S. John himself has shewn that the devil had long been at work with Judas. The meaning is that of the received reading, but more awkwardly expressed. -To betray" is literally S. John's favourite form -in order that he should betray." The traitor's name is given in full for greater solemnity, and in the true text comes last for emphasis. Note the position of Iscariot, confirming the view (see on John 6:71) that the word is a local epithet rather than a proper name.