Ka'b ibn Ujrah

Kaʿb ibn ʿUjrah was a Companion present in iḥrām at al-Ḥudaybiyyah (6 AH) who suffered so badly from a lice infestation in his hair that it made him ill. Seeing his distress, the Prophet ﷺ told him to shave his head despite being in iḥrām and to offer expiation (fidyah), fasting three days, feeding six needy people, or sacrificing a sheep. His case became the occasion for the Qurʾānic ruling (al-Baqarah 2:196) on shaving during iḥrām for a medical need, and the standing precedent that a pilgrim may break an iḥrām restriction for a legitimate necessity and pay a fidyah for it.