The last words of the adhan of Hazrat Abu Mahzoorah and Hazrat Bilal used to be "As-salatu khayrun minan-nawm."

Hazrat Suwaid bin Ghaflah sent this message to his muezzin that when you reach "Hayya 'ala al-Falah" then say "As-salatu khayrun min an-nawm" because this was the adhan of Hazrat Bilal.

Ismail narrates that once the muezzin of Hazrat Umar came to inform him of the morning adhan and said: "As-salatu khayrun minan-nawm" (Prayer is better than sleep). Hazrat Umar liked these words very much and instructed the muezzin to make these words a part of his adhan.

Hazrat Nafi' narrates that Hazrat Ibn Umar (may Allah be pleased with them) used to say these words in his adhan: "As-salatu khayrun minan-nawm."

Muhammad says that saying "As-salatu khayrun minan-nawm" in the adhan is not Sunnah.

Hazrat Saeed bin Musayyib narrates that Hazrat Bilal came to inform the Messenger of Allah (peace and blessings be upon him) about the time of prayer. He was told that the Messenger of Allah (peace and blessings be upon him) was sleeping. Hazrat Bilal then called out loudly: "As-salatu khayrun minan-nawm" (Prayer is better than sleep). After that, these words became a part of the adhan.

Hazrat Hisham bin Urwah narrates that his father used to say these words in his adhan: "As-salatu khayrun minan-nawm, as-salatu khayrun minan-nawm, Allahu Akbar, Allahu Akbar, la ilaha illallah."

Hazrat Qasim bin Mukhaymirah used to say these words in the tasweeb of his adhan: "As-salatu khayrun minan-nawm, as-salatu khayrun minan-nawm."

Hazrat Hisham states that according to Hasan and Muhammad, the meaning of Tasweeb was that these words should be said: Hayya 'ala-s-Salah, As-Salatu Khayrun Minan-Nawm.

Hazrat Imran bin Abi Al-Ja'd narrates that Hazrat Aswad bin Yazid heard the muezzin say these words in the Fajr adhan: "As-salatu khayrun minan-nawm" (Prayer is better than sleep). So he said that do not add to the adhan those words which are not a part of it.