What is the minimum extent of shaved hair on the head that necessitates *damm* (blood sacrifice)?
Chapter on Ransom (Fidyah) and Penalty for Hunting
Al-Mughni
Book of Hajj
Primary text
The required amount of shaved hair on the head necessitating *damm* is four hairs or more. This position is held by Al-Hasan, 'Ata', Ibn 'Uyaynah, Al-Shafi'i, and Abu Thawr. The justification is that any amount of human hair to which the absolute term 'shaved' can be applied is sufficient for *damm* to become obligatory, similar to a quarter of the head.
Supporting text
Abu Hanifa holds that *damm* is not obligatory unless a quarter of the head is shaved, arguing that a quarter represents the whole in certain contexts. Malik mandates *damm* if the amount shaved is enough to clear away harm, such as removing the hair causing irritation.