Musannaf Ibn Abi Shayba 3:4072

Abu Bakr narrated to us, he said: Hushaym narrated to us, from Abd al-Malik, from Ata, from Zayd ibn Khalid al-Juhani, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Pray in your houses, and do not take them as graves."