Sayyiduna Ka'b bin Ujrah (may Allah be pleased with him) narrates: The Prophet Muhammad (peace and blessings be upon him) passed by me while I was lighting a fire under my cooking pot, and lice were falling from my head. The Prophet (peace and blessings be upon him) asked: "Are the lice on your head causing you trouble?" I replied: "Yes." The Prophet (peace and blessings be upon him) said: "Then offer a sacrifice, or fast for three days, or feed six needy people (and shave your head)."