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