Who should betray him - Greek: "He knew him who was about to betray him."

For he knew who should betray him,.... That is, Jesus, as Beza's ancient copy, and the Syriac and Persic versions read. This he knew from the beginning; not only from the beginning of his ministry, when he chose his twelve apostles, but from the beginning of time, yea, from everlasting; this being fixed by the determinate counsel of God, which he, as the omniscient God, was privy to: he knew what preparations were making, and how things were then working, in order to bring it about; he knew that Satan had already put it into Judas's heart, and that he had consented to it;
therefore, said he, ye are not all clean: he does not mention his name, though he could have done so, it not being as yet proper to make so full a discovery of him, before the matter was ripe for execution; and also to put all the disciples upon examination of themselves.