Cross reference
Mark 14:19
19 And they began to be sorrowful, and to say unto him one by one, Is it I? and another said, Is it I?
Matthew 26:22
22 And they were exceeding sorrowful, and began every one of them to say unto him, Lord, is it I?
Luke 22:21-23
21 But, behold, the hand of him that betrayeth me is with me on the table.
22 And truly the Son of man goeth, as it was determined: but woe unto that man by whom he is betrayed!
23 And they began to enquire among themselves, which of them it was that should do this thing.
John 13:22
22 Then the disciples looked one on another, doubting of whom he spake.