Musnad Abu Ya'la al-Mawsili 148:65

Abu Bakr ibn Abi Shaybah narrated to us, Waki' narrated to us, from Uthman ibn Sa'd, who said: I heard Anas ibn Malik saying: When the Messenger of Allah (peace and blessings of Allah be upon him) would stop at a place, he would not depart from it until he had bid it farewell with two rak'ahs.