John 13-18
13The Pharisees challenged him, "Here you are, appearing as your own witness; your testimony is not valid."
14Jesus answered, "Even if I testify on my own behalf, my testimony is valid, for I know where I came from and where I am going. But you have no idea where I come from or where I am going. 15You judge by human standards; I pass judgment on no one. 16But if I do judge, my decisions are right, because I am not alone. I stand with the Father, who sent me. 17In your own Law it is written that the testimony of two men is valid. 18I am one who testifies for myself; my other witness is the Father, who sent me."
John 8:27-30
27They did not understand that he was telling them about his Father. 28So Jesus said, "When you have lifted up the Son of Man, then you will know that I am the one I claim to be and that I do nothing on my own but speak just what the Father has taught me. 29The one who sent me is with me; he has not left me alone, for I always do what pleases him." 30Even as he spoke, many put their faith in him.
Luke 16:29-32 (New International Version)
29"Abraham replied, 'They have Moses and the Prophets; let them listen to them.'
30" 'No, father Abraham,' he said, 'but if someone from the dead goes to them, they will repent.'
31"He said to him, 'If they do not listen to Moses and the Prophets, they will not be convinced even if someone rises from the dead.' "