It is narrated from Hazrat Hudhaifa (may Allah be pleased with him). He says that Hazrat Ali (may Allah be pleased with him) went to visit a man who was ill. He saw a thread tied on the man's wrist. He asked, "What is this?" The man replied, "This is a thread that has been given to me after being blown upon (for healing)." Upon this, Hazrat Ali (may Allah be pleased with him) broke it. Then he said: "If you had died, I would not have performed your funeral prayer."