The confirmed wordings of Adhan

Q 2: Before the Adhan (call to prayer), Al-Mu'adhin (A caller for prayer) recites this Ayah: (Part No. 2; Page No. 211)  And who is better in speech than he who [says: "My Lord is Allâh (believes in His Oneness)," and then stands firm (acts upon His Order), and] invites (men) to Allâh’s (Islâmic Monotheism), and does righteous deeds, and says: "I am one of the Muslims." He repeats every phrase twice and adds "come to best of actions" and he also does this in the Iqamah (call to start the Prayer).

A: No Dhikr (Remembrance of Allah) or Qur'an is to be recited before Adhan or any act of worship because this was not reported from the Prophet (peace be upon him). A Muslim must limit himself to the wordings of Adhan which are authentically reported from the Prophet (peace be upon him) which is the Adhan Bilal recited in Al-Madinah. It consists of fifteen phrases: Saying, "Allah Akbar" (Allah is the Greatest) in the beginning four times. The testimony of "Ashhadu Anna La Ilaha Illal Allah" (There is no God but Allah) twice. "Ashhadu Anna Muhammadan Rasoulullah" (The testimony that Muhammad is the Messenger of Allah) twice. "Hay `Ala Al-Salah" (come to Salah) twice. "Hay `Ala Al-Falah" (Come to success) twice. (and says after them in the Adhan of the Fajr (Morning) Prayer: "Al-Salah Khayr min Al-Nawm" (Salah is better than sleep) twice). Saying, "Allah Akbar" (Allah is the Greatest) twice. And "La Ilaha Illa Allah" (There is no God but Allah) once.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.