Musannaf Ibn Abi Shayba 3:5197

Waki’ narrated to us, Sufyan narrated to us, from ‘Amr ibn Yahya ibn ‘Umarah al-Mazini, from his father, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "The entire earth is a place of prostration, except for the graveyard and the bathhouse."