Narrated from Sayyiduna Ruwaifi’ bin Thabit Ansari (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: O Ruwaifi’! It is possible that your life will be prolonged, so inform the people that whoever ties a knot in his beard, or puts on a string necklace, or uses animal dung or bone for istinja (purification), then Muhammad (peace and blessings be upon him) is free from him. In another narration it is stated: Such a person will be free from that which was revealed to Muhammad (peace and blessings be upon him).