Azazel promises to resurrect John so Mary can have a normal life with him if she gives Azazel permission to enter her house in ten years. Though Dean tries to intervene with the Colt, Mary makes the deal and John is resurrected while Azazel flees Samuel's body before he can wake up with no memories of being dead.
If you are asking what John said to Dean right before he died, he told Dran that Sam might turn evil because of what the Yellow Eyed Demon dod to Sam as an infant. He said if you can't save him, you'll have to kill him.