That Allah's Messenger (ﷺ) saw him with the lice falling (from his head) on his face. Allah's Messenger (ﷺ) said, "Are your lice troubling you? Ka`b said, "Yes." Allah's Messenger (ﷺ) thus ordered him to shave his head while he was at Al-Hudaibiya. Up to then there was no indication that all of them would finish their state of Ihram and they hoped that they would enter Mecca. Then the order of Al-Fidya was revealed, so Allah's Messenger (ﷺ) ordered Ka`b to feed six poor persons with one Faraq of food or slaughter a sheep or fast for three days.
Sahih al-Bukhari Book 64, Hadith 202
← Previous Hadith The Prophet (ﷺ) went out in the company of 1300 to 1500 of his companions in the year of Al-Hudaibiya, and when they reached Dhul-Hulaifa, he garlanded and marked his Hadi and assumed the state of Ihram.

Sahih al-Bukhari Book 64, Hadith 201 Next Hadith → Once I went with `Umar bin Al-Khattab to the market. A young woman followed `Umar and said, "O chief of the believers! My husband has died, leaving little children. By Allah, they have not even a sheep's trotter to cook; they have no farms or animals. I am afraid that they may die because of hunger, and I am the daughter of Khufaf bin Ima Al-Ghafari, and my father witnessed the Pledge of allegiance) of Al-Hudaibiya with the Prophet.' `Umar stopped and did not proceed, and said, "I welcome my near relative." Then he went towards a strong camel which was tied in the house, and carried on to it, two sacks he had loaded with food grains and put between them money and clothes and gave her its rope to hold and said, "Lead it, and this provision will not finish till Allah gives you a good supply." A man said, "O chief of the believers! You have given her too much." "`Umar said disapprovingly. "May your mother be bereaved of you! By Allah, I have seen her father and brother besieging a fort for a long time and conquering it, and then we were discussing what their shares they would have from that war booty."

Sahih al-Bukhari Book 64, Hadith 203