Musannaf Ibn Abi Shayba 2:49

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Isra’il, from Hakim ibn Jubayr, from ‘Imran ibn Abi al-Ja’d, that he heard al-Aswad ibn Yazid [saying] when he heard a mu’adhdhin saying in the dawn [call to prayer]: "Prayer is better than sleep," he said: "They do not add to the adhan that which is not of it."