Musannaf Ibn Abi Shayba 27:158

Waki’ narrated to us, from Badr ibn ‘Uthman, from ‘Ikrimah, who said: When revelation came to the Prophet, may Allah bless him and grant him peace, the Quraysh said, "Muhammad has been cut off (abtar)." Then was revealed: "Indeed, your enemy is the one cut off (al-abtar)." The one who threw that at you is the one cut off (al-abtar).