And Yahya ibn Yahya narrated to us, saying: Khalid ibn Abdullah informed us, from Khalid, from Abu Qilabah, from Abd al-Rahman ibn Abi Layla, from Ka'b ibn Ujrah, may Allah be pleased with him, that the Messenger of Allah, peace and blessings be upon him, passed by him during the time of al-Hudaybiyyah and said to him: "Have the lice of your head harmed you?" He said: "Yes." The Prophet, peace and blessings be upon him, said to him: "Shave your head, then sacrifice a sheep as an offering, or fast three days, or feed three sa's of dates to six poor persons."