What does John 13:26 mean?
Jesus predicted that one of the men present at this last supper would betray Him (John 13:21–22). Peter signaled to John, who is directly to Jesus' right, to ask who this person is (John 13:23–24). As was custom, the men are reclining on their left sides around the food. That places John to the right of Jesus, facing away from Him. In order to ask his question, John must lean back (John 13:25). He can probably hear Jesus better than anyone else, but he's in an awkward position to see. That would explain why, so far as we can tell, neither John nor the others realize Jesus has identified Judas as the traitor.Matthew, again, includes details which John does not feel the need to repeat (Matthew 26:22–23). While John refers to Judas taking this food and then leaving (John 13:27–30), Matthew indicates that Judas directly asks Jesus if the prediction is about him (Matthew 26:25). While Matthew indicates that Jesus gives Judas a direct answer, no one seems to respond. John, here, fills in what Matthew leaves out. In the emotion and hubbub of the moment, this exchange between Jesus and Judas is partly lost. Different disciples hear different things, but no one gets enough information to clearly understand.
Sharing food with someone carried an implication of friendship and peace in the ancient world. This is why phrases like "breaking bread" and such are used as expressions of cooperation. Though He knows what will happen, Jesus has recently washed Judas' feet (John 13:2–5). Here He shows one last expression of friendship to the man plotting His death (Matthew 26:14–16).