Ameer al-Momineen (a.s) quoted on the authority of God's Prophet (a.s)
“Whenever you hear a tradition which contains contradictions, it is not what I have said, even if they claim I have said it. And if you hear a tradition that is not contradictory by itself, it is from me. Whoever sees me dead is similar to one who sees me when I am alive. I am a witness for whoever comes to visit my tomb, and I shall be his witness in the Hereafter.”