Musannaf Ibn Abi Shayba 34:263

35995. Abd al-Wahhab ibn ‘Ata narrated to us, from Ibn ‘Awn, from Muhammad, who said: The first to introduce the Adhan for [the prayer of] al-Fitr and al-Adha was Marwan. I found in my book, from Suwayd ibn ‘Amr, from Hammad ibn Salamah, from Qays ibn Sa‘d, from Tawus, who said: The first to perform the *tathwib* (calling out) in the dawn prayer was Bilal during the time of Abu Bakr; when he would say, "Hayya ‘ala al-falah" (Come to success), he would say, "As-salatu khayrun min an-nawm" (Prayer is better than sleep) twice.