I am so sorry to hear about your friend John.
I offer the following prayer:
Dear Lord and Savior, I ask you to extend your blessings to John as he lives through the final moments of his life. Help him in the his final hours that he may not lose courage but seek to do your will to the end. May he fight the good fight for you. If it your will, at the moment of death, bring him into your eternal kingdom. Amen.