I testify that there is no god but Allah, I testify that there is no god but Allah; I testify that Muhammad is the Messenger of Allah, I testify that Muhammad is the Messenger of Allah. Lowering your voice while saying them (these words). Then you must raise your voice in making the testimony: I testify that there is no god but Allah, I testify there is no god but Allah; I testify Muhammad is the Messenger of Allah, I testify Muhammad is the Messenger of Allah. Come to prayer, come to prayer; come to salvation, come to salvation. If it is the morning prayer, you must pronounce; prayer is better than sleep, prayer is better than sleep, Allah is most great; there is no god but Allah.
Sunan Abi Dawud Book 2, Hadith 110
← Previous Hadith when the Messenger of Allah (ﷺ) ordered a bell to be made so that it might be struck to gather the people for prayer, a man carrying a bell in his hand appeared to me while I was asleep, and I said; servant of ‘abd Allah, will you sell the bell? He asked; what will you do with it? I replied; we shall use it to call the people to prayer. He said; should I not suggest you something better than that. I replied: certainly. Then he told me to say: Allah is most great, Allah is most great, Allah is most great, Allah is most great. I testify that there is no god but Allah, I testify that Muhammad is the Messenger of Allah. Come to pray, come to pray; come to salvation; come to salvation. Allah is most great, Allah is most great. I testify that there is no god but Allah. He then moved backward a few steps and said: when you utter the IQAMAH, you should say: Allah is most great, Allah is most great. I testify that there is no god but Allah, I testify that Muhammad is the Messenger of Allah. Come to prayer, come to salvation. The time for prayer has come, the time for prayer has come: Allah is most great, Allah is most great. There is no god but Allah. When the morning came, I came to the Messenger of Allah (May peace be upon him) and informed him of what I had seen in the dream. He said: it is a genuine vision, and he then should use it to call people to prayer, for he has a louder voice than you have. So I got up along with Bilal and began to teach it to him and he used it in making the call to prayer. ‘Umar b. al-khattab (Allah be pleased with him) heard it while he was in his house and came out trailing his cloak and said: Messenger of Allah. By him who has sent you with the truth, I have also seen the kind of thing as has been shown to him. The Messenger of Allah (May peace be upon him) said: To Allah be the praise. Abu Dawud said; Al-Zuhri narrated this tradition in a similar way from Sa’id b. al-Musayyib on the authority of ‘Abd Allah b. Zaid. In this version Ibn Ishaq narrated from al-Zuhri: Allah is most great. Allah is most great, Allah is most great, Allah is most great. Ma;mar and yunus narrated from al-Zuhri; Allah is most great, Allah is most great. They did not report it twice again.

Sunan Abi Dawud Book 2, Hadith 109 Next Hadith → He (the prophet) taught me IQAMAH (to pronounce each phrase) twice: Allah is most great. Allah is most great. I testify that there is no god but Allah. I testify that there is no god but Allah; I testify that Muhammad is the Messenger of Allah, I testify that Muhammad is the Messenger of Allah: come to prayer, come to prayer: come to salvation, come to salvation: Allah is most great. Allah is great; there is no god but Allah.

Abu Dawud said: The narrator ‘Abd al-Razzaq said; You pronounce IQAMAH for announcing the prayer; you must say twice: the time for prayer has come, the time for prayer has come. (The Prophet said to Abu Mahdhurah): did you listen (to me)? Abu Mahdhurah would not have the hair of his forehead cut, nor would he separate them (from him) because the Prophet (ﷺ) wiped over them.

Sunan Abi Dawud Book 2, Hadith 111