Hadith 500800
Chapter 2: Purity - كتاب الطهارة
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَزِيدَ بْنِ عَبْدِ اللَّهِ بْنِ قُسَيْطٍ اللَّيْثِيِّ، أَنَّهُ رَأَى سَعِيدَ بْنَ الْمُسَيَّبِ رَعَفَ وَهُوَ يُصَلِّي فَأَتَى حُجْرَةَ أُمِّ سَلَمَةَ زَوْجِ النَّبِيِّ صلى الله عليه وسلم فَأُتِيَ بِوَضُوءٍ فَتَوَضَّأَ ثُمَّ رَجَعَ فَبَنَى عَلَى مَا قَدْ صَلَّى .
Yahya related to me from Malik from Yazid ibn Abdullah Qusayt al- Laythi that he saw Said ibn al-Musayyab having a nose-bleed while praying. He went off to the room of Umm Salama, the wife of the Prophet, may Allah bless him and grant him peace, and water was brought to him and he did wudu. He then returned and completed his prayer.
Reference Muwatta Malik 500800
USC-MSA web (English) reference : Book 2, Hadith 50