Musannaf Ibn Abi Shayba 3:5169

Zakariya ibn ‘Adi narrated to us, from ‘Ubayd Allah ibn ‘Umar, from Zayd ibn Abi Unaysa, from ‘Amr ibn Murrah, from ‘Abd Allah ibn al-Harith al-Najrani, who said: My grandfather narrated to me, saying: I heard the Prophet, may Allah bless him and grant him peace, five days before he died, and he was saying: "Behold, those who were before you used to take the graves of their prophets and their righteous people as places of worship. Behold, do not take graves as places of worship, for I forbid you from that."