Language:
كتاب الحيض
6  
Menstrual Periods
(2)
Chapter: The washing of the husband's head and the combing of his hair by a menstruating wife
(2)
باب غَسْلِ الْحَائِضِ رَأْسَ زَوْجِهَا وَتَرْجِيلِهِ
Sahih al-Bukhari 296

Narrated `Urwa:

A person asked me, "Can a woman in menses serve me? And can a Junub woman come close to me?" I replied, "All this is easy for me. All of them can serve me, and there is no harm for any other person to do the same. `Aisha told me that she used to comb the hair of Allah's Messenger (ﷺ) while she was in her menses, and he was in I`tikaf (in the mosque). He would bring his head near her in her room and she would comb his hair, while she used to be in her menses."

حَدَّثَنَا إِبْرَاهِيمُ بْنُ مُوسَى، قَالَ أَخْبَرَنَا هِشَامُ بْنُ يُوسُفَ، أَنَّ ابْنَ جُرَيْجٍ، أَخْبَرَهُمْ قَالَ أَخْبَرَنِي هِشَامٌ، عَنْ عُرْوَةَ، أَنَّهُ سُئِلَ أَتَخْدُمُنِي الْحَائِضُ أَوْ تَدْنُو مِنِّي الْمَرْأَةُ وَهْىَ جُنُبٌ فَقَالَ عُرْوَةُ كُلُّ ذَلِكَ عَلَىَّ هَيِّنٌ، وَكُلُّ ذَلِكَ تَخْدُمُنِي، وَلَيْسَ عَلَى أَحَدٍ فِي ذَلِكَ بَأْسٌ، أَخْبَرَتْنِي عَائِشَةُ أَنَّهَا كَانَتْ تُرَجِّلُ ـ تَعْنِي ـ رَأْسَ رَسُولِ اللَّهِ صلى الله عليه وسلم وَهِيَ حَائِضٌ، وَرَسُولُ اللَّهِ صلى الله عليه وسلم حِينَئِذٍ مُجَاوِرٌ فِي الْمَسْجِدِ، يُدْنِي لَهَا رَأْسَهُ وَهْىَ فِي حُجْرَتِهَا، فَتُرَجِّلُهُ وَهْىَ حَائِضٌ‏.‏
Reference : Sahih al-Bukhari 296
In-book reference : Book 6, Hadith 3
USC-MSA web (English) reference : Vol. 1, Book 6, Hadith 295
  (deprecated numbering scheme)