Sahih Bukhari

Narrated Ka`b bin Ujra:The Prophet (ﷺ) came to me at the time of Al-Hudaibiya Pledge while lice were falling on my face. He said, ""Are the lice of your head troubling you?"" I said, ""Yes."" He said, ""Shave your head and fast for three days, or feed six poor persons, or slaughter a sheep as sacrifice."" (The sub-narrator, Aiyub said, ""I do not know with which of these three options he started)