John 13:21

‘The disciples looked at one another not sure of whom he spoke'.

Nothing that Judas had done had brought Judas under suspicion, although John appears to have been a little unsure of him for other reason (John 12:6). However, there is a great deal of difference between petty theft and open betrayal, and John might even have seen Judas' dishonesty as the betrayal Jesus was speaking about. The verb is continuous. It suggests a stunned silence as they looked from one to another again and again. They were totally baffled, and not a little uncomfortable.. The other Gospels tell us that they asked, aware of their own possible frailty, ‘Lord, is it I?' They knew Jesus must be right and it awakened their worst nightmares and fears about themselves. They were not, however, thinking of quite such a total betrayal as Judas would perpetrate. They were probably thinking in terms of ‘letting the Lord down'.