Sayyiduna Abu Mahdhurah (may Allah be pleased with him) said: I set out with ten youths with the Prophet (peace and blessings be upon him) towards Hunayn. They gave the adhan, and we too stood up and began giving the adhan mockingly. The Prophet (peace and blessings be upon him) said: "Bring these youths to me." He (peace and blessings be upon him) said: "Give the adhan." They gave the adhan, and my voice was the loudest among them. He (peace and blessings be upon him) said: "Yes, this is the one whose voice I heard. Go and give the adhan for the people of Makkah, and tell Attab bin Usayd: 'The Messenger of Allah (peace and blessings be upon him) has ordered me to give the adhan for the people of Makkah.'" He (peace and blessings be upon him) said: "Say: 'Allahu akbar, Allahu akbar, Allahu akbar, Allahu akbar' (Allah is the Greatest, Allah is the Greatest, Allah is the Greatest, Allah is the Greatest), 'Ash-hadu an la ilaha illallah' (I bear witness that there is no god but Allah) (twice), 'Ash-hadu anna Muhammadan rasulullah' (I bear witness that Muhammad is the Messenger of Allah) (twice); then say again: 'Ash-hadu an la ilaha illallah' (I bear witness that there is no god but Allah) (twice), 'Ash-hadu anna Muhammadan rasulullah' (I bear witness that Muhammad is the Messenger of Allah) (twice), 'Hayya 'alas-salah' (Come to the prayer) (twice), 'Hayya 'alal-falah' (Come to success) (twice), 'Allahu akbar, Allahu akbar' (Allah is the Greatest, Allah is the Greatest), 'La ilaha illallah' (There is no god but Allah). And when you give the iqamah, say twice: 'Qad qamatis-salah, qad qamatis-salah' (The prayer has begun, the prayer has begun)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1847