(the Pharisees being inform'd what the people rumour'd concerning him, they and the chief priests sent their officers to seize him.)

and it was upon the rumour of this miracle, that the people crowded to him.

So the rumor spread among the brothers that this disciple wasn't going to die. Yet Jesus didn't say to Peter that he wasn't going to die, but, "If it's my will for him to remain until I come back, how does that concern you?"