Musannaf Ibn Abi Shayba 3:604

Yahya ibn Adam narrated to us, from Mufaddal ibn Muhalhal, from Bayan, from Qays, that Bilal saw a man who was not completing his bowing (ruku') nor his prostration (sujud). He said: "If this man were to die, he would die upon other than the religion of 'Isa ibn Maryam."