It was narrated from Abu Mahdhurah that the Prophet (ﷺ) sat him down and taught him the Adhan letter by letter. (One of the narrators) Ibrahim said, "It is like this Adhan of ours". I said[1]:
"Recite it to me." He said, "Allahu Akbar, Allahu Akbar (Allah is the greatest, Allah is the greatest), Ashhadu an la ilaha illallah (I bear witness that there is none worthy of worship except Allah) - twice. Ashhadu anna Muhammadan Rasulallah (I bear witness that Muhammad is the messenger of Allah) - twice. Then he said in a lower voice which those around him could here: Ashhadu an la ilaha ill-Allah (I bear witness that there is none worthy of worship except Allah) - twice. Ashhadu anna Muhammadan Rasulallah (I bear witness that Muhammad is the messenger of Allah) - twice, Hayya'ala as-salah (come to prayer) - twice, Hayya alal-falah (come to prosperity) - twice, Allahu Akbar Allahu Akbar la ilaha illallah (Allah is the Greatest, Allah is the Greatest, there is none worthy of worship except Allah).

[1] Bishir bin Mu'adh who heard it from Ibrahim, and from whom An-Nasa'i is reporting it, is the one who is asking for the Adhan to be recited to him.