[Machine] I heard Anas saying that the Messenger of Allah ﷺ used to go to the bathroom and I would follow him along with a young boy from the Ansar, carrying a container of water, so he would clean himself with it after defecating. This narration is found in Sahihayn (i.e. Sahih Bukhari and Sahih Muslim) from the hadith of Shu'bah ibn al-Hajjaj.
سَمِعْتُ أَنَسًا يَقُولُ كَانَ رَسُولُ اللهِ ﷺ يأْتِي الْخَلَاءَ فَأَتَّبِعُهُ أَنَا وَغُلَامٌ مِنَ الْأَنْصَارِ بِإِدَاوَةٍ مِنْ مَاءٍ فَيَسْتَنْجِي بِهَا مُخَرَّجٌ فِي الصَّحِيحَيْنِ مِنْ حَدِيثِ شُعْبَةَ بْنِ الْحَجَّاجِ