John 6:51 (WEB) - 51 I am the living bread which came down out of heaven. If anyone eats of this bread, he will live forever. Yes, the bread which I will give for the life of the world is my flesh.”
John 6:53, 53 So Jesus said to them, “Truly, truly, I say to you, unless you eat the flesh of the Son of man and drink his blood, you have no life in you; - RSV
John 6:64 (WEB) - 64 But there are some of you who don’t believe.” For Jesus knew from the beginning who they were who didn’t believe, and who it was who would betray him.