عَنْ عَائِشَةَ رَضِيَ اللَّهُ عَنْهَا قَالَتْ: كُنْتُ أُرَجِّلُ رَأْسَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَأَنَا حَائِض

Nafi‘ quoted Ibn ‘Umar as saying he had heard the Prophet forbidding qaza'. Nafi' was asked what qaza’ was and replied that it was having part of a boy’s head shaved arid leaving part unshaven. (Bukhari and Muslim.) Some made the explanation a part of the tradition.