Musannaf Ibn Abi Shayba 18:178

Abu Bakr narrated to us, he said: Zayd ibn al-Hubab narrated to us, he said: al-Zubayr ibn Junada narrated to us, he said: I asked 'Ata' about a man who struck a man, and his hearing was lost, and he had been hearing. He said: He is to be left alone, and when he falls into a deep sleep, one should make a loud noise around him. If he does not wake up, then the blood money (diyah) is due. And if he wakes up, then it is a discretionary penalty (hukumah).