That Messenger of Allah ﷺ saw him with the lice falling (from his head) on his face. Messenger of Allah ﷺ said, "Are your lice troubling you? Kaʿb said, "Yes." Messenger of Allah 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 Messenger of Allah ﷺ ordered Kaʿb to feed six poor persons with one Faraq of food or slaughter a sheep or fast for three days.
أَنَّ رَسُولَ اللَّهِ ﷺ رَآهُ وَقَمْلُهُ يَسْقُطُ عَلَى وَجْهِهِ فَقَالَ أَيُؤْذِيكَ هَوَامُّكَ قَالَ نَعَمْ فَأَمَرَهُ رَسُولُ اللَّهِ ﷺ أَنْ يَحْلِقَ وَهْوَ بِالْحُدَيْبِيَةِ لَمْ يُبَيِّنْ لَهُمْ أَنَّهُمْ يَحِلُّونَ بِهَا وَهُمْ عَلَى طَمَعٍ أَنْ يَدْخُلُوا مَكَّةَ فَأَنْزَلَ اللَّهُ الْفِدْيَةَ فَأَمَرَهُ رَسُولُ اللَّهِ ﷺ أَنْ يُطْعِمَ فَرَقًا بَيْنَ سِتَّةِ مَسَاكِينَ أَوْ يُهْدِيَ شَاةً أَوْ يَصُومَ ثَلاَثَةَ أَيَّامٍ