Language:
كتاب الصلاة
8  
Prayers (Salat)
(19)
Chapter: If the clothes of a prayer person in prostration touched his wife [would that make his Salat (prayer) invalid]?
(19)
باب إِذَا أَصَابَ ثَوْبُ الْمُصَلِّي امْرَأَتَهُ إِذَا سَجَدَ
Sahih al-Bukhari 379

Narrates `Abdullah bin Shaddad:

Maimuna said, "Allah's Messenger (ﷺ) was praying while I was in my menses, sitting beside him and sometimes his clothes would touch me during his prostration." Maimuna added, "He prayed on a Khumra (a small mat sufficient just for the face and the hands while prostrating during prayers).

حَدَّثَنَا مُسَدَّدٌ، عَنْ خَالِدٍ، قَالَ حَدَّثَنَا سُلَيْمَانُ الشَّيْبَانِيُّ، عَنْ عَبْدِ اللَّهِ بْنِ شَدَّادٍ، عَنْ مَيْمُونَةَ، قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُصَلِّي وَأَنَا حِذَاءَهُ وَأَنَا حَائِضٌ وَرُبَّمَا أَصَابَنِي ثَوْبُهُ إِذَا سَجَدَ‏.‏ قَالَتْ وَكَانَ يُصَلِّي عَلَى الْخُمْرَةِ‏.‏
Reference : Sahih al-Bukhari 379
In-book reference : Book 8, Hadith 31
USC-MSA web (English) reference : Vol. 1, Book 8, Hadith 376
  (deprecated numbering scheme)