Musannaf Ibn Abi Shaybah 2185 — Those who said in the adhan: Prayer

Imran bin Abi al-Ja'd said: Al-Aswad bin Yazid heard a muezzin say these words in the Fajr adhan: 'al-salatu khayrun min al-nawm (prayer is better than sleep)'. He said: Do not add to the adhan words that are not part of it.