Sahih Bukhari | Volume 3 | Hadith Number 42

Narrated by Ka'b bin 'Umra
Allah's Apostle stood beside me at Al-Hudaibiya and the lice were falling from my head in great number. He asked me, "Have your lice troubled you?" I replied in the affirmative. He ordered me to get my head shaved. Ka'b added, "This Holy Verse: 'And if any of you is ill, or has ailment in his scalp (2:196), etc. was revealed regarding me. "The Prophet then ordered me either to fast three days, or to feed six poor persons with one Faraq (three Sas) (of dates), or to slaughter a sheep, etc (sacrifice) whatever was available.