Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 103
Narrated Anas bin Malik:
Allah's Apostle visited a household among the Ansars, and he took a meal with them. When he intended to leave, he asked for a place in that house for him, to pray so a mat sprinkled with water was put and he offered prayer over it, and invoked for Allah's Blessing upon them (his hosts).