Charles Ellicott Commentary Matthew 26:25

"And Judas, who betrayed him, answered and said, Is it I, Rabbi? He saith unto him, Thou hast said." — Matthew 26:25 (ASV)

Then Judas, who betrayed him... The words appear to have been spoken in a spirit of reckless defiance, which John indicates by saying, “after the sop Satan entered into him” (John 13:27). Did his Master (he calls Him by the customary title of honor, Rabbi) indeed know his guilt? It would appear from John’s narrative (John 13:29) that the dreadful answer, “You have said,” was not heard by everyone.

All they heard was the command, “What you do, do quickly.” Some of them, likely the rest who were not aware of the secret signal, thought the command referred to a matter connected with his customary work as the treasurer for the group. They assumed he was to buy what was needed for the feast (likely the customary solemn meal, or Chagigah, of the day that followed the Passover Supper) or to give alms to the poor.

Judas, however, understood the meaning of the words and immediately went out (John 13:27–30). It follows from this view of the sequence of events that although he had eaten bread with his Master, he did not partake of the bread and the cup that were to be the signs of the New Covenant. At this stage, John inserts the words about the new commandment, “that you should love one another,” which was embodied in that act of fellowship.