It is narrated from Hazrat Anas bin Malik (may Allah be pleased with him) that one of my uncles once invited the Prophet (peace and blessings of Allah be upon him) for a meal and said, "O Messenger of Allah (peace and blessings of Allah be upon him)! I wish that you eat food at my house and pray there." So the Prophet (peace and blessings of Allah be upon him) came. There was a mat in the house which had become old and black. The Prophet (peace and blessings of Allah be upon him) ordered it to be placed in a corner, it was dusted and water was sprinkled on it. Then the Prophet (peace and blessings of Allah be upon him) prayed there and we also prayed with the Prophet (peace and blessings of Allah be upon him).