Musnad Ahmad 32:163

Isma'il ibn Ibrahim narrated to us, Ibn 'Awn narrated to us, Anas ibn Sirin informed us, from 'Abd al-Hamid ibn al-Mundhir ibn al-Jarud, from Anas ibn Malik, who said: "Some of my paternal uncles prepared food for the Prophet, may Allah bless him and grant him peace." He said: "O Messenger of Allah, I would like for you to eat in my house and pray in it." He said: "So he came to him, and there was a mat in the house of those mats. He ordered a side of it to be swept and sprinkled [with water], so he prayed and we prayed with him."