(2) The Book of Purification
كتاب الطهارة
(21) Chapter: Cleaning oneself with water after defecating
(21) باب الاِسْتِنْجَاءِ بِالْمَاءِ مِنَ التَّبَرُّزِ ‏‏
Sahih Muslim 270 

Anas b. Malik reported:

The Messenger of Allah (ﷺ) entered an enclosure while a servant was following him with a jar of water and he was the youngest amongst us and he placed it by the side of a lote-tree. When the Messenger of Allah, (ﷺ) relieved himself, he came out and had cleansed himself with water.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا خَالِدُ بْنُ عَبْدِ اللَّهِ، عَنْ خَالِدٍ، عَنْ عَطَاءِ بْنِ أَبِي مَيْمُونَةَ، عَنْ أَنَسِ بْنِ مَالِكٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم دَخَلَ حَائِطًا وَتَبِعَهُ غُلاَمٌ مَعَهُ مِيضَأَةٌ هُوَ أَصْغَرُنَا فَوَضَعَهَا عِنْدَ سِدْرَةٍ فَقَضَى رَسُولُ اللَّهِ صلى الله عليه وسلم حَاجَتَهُ فَخَرَجَ عَلَيْنَا وَقَدِ اسْتَنْجَى بِالْمَاءِ ‏.‏
Reference : Sahih Muslim 270
In-book reference : Book 2, Hadith 86
USC-MSA web (English) reference : Book 2, Hadith 517
  (deprecated numbering scheme)