The history of Adhan (Azan)

When the Prophet (salAllahu alayhi wasalam) and the Muslims of Makkah had made Hijrah to Madinah, the Prophet (saw) had built the first ever masjid called masjid al-Nabi. The Muslims used to gather and wait for the time of salah (prayer) to be announced by the Prophet (saw) so they could all pray in Jama'ah (congregation).

In Makkah, the number of Muslims was small, so they would make Jama'ah without any call. However by the second year of Hijrah, the number of Muslims had increased. The people use to announce in a loud voice, "As-Salat ul-Jami'ah - the salah for jama'ah is ready." Those who heard this call came to join the Salah. Muslims later felt that they needed to find a better way to inform people to come to prayer. Since there was no adhan given, it was quite difficult for the Muslims to know when to stop what they were doing and go to the masjid for salah.

One day, the Prophet (saw) asked the Sahabas about a way to call everyone to salah five times a day. Some Sahaba suggested that the Muslims, like the Jews, should blow a horn to announce the time for the Salah. Others said, the Muslims might ring bells as the Christians do in their churches. A few proposed that the Muslims, like the fire-worshippers, kindle a fire to call people to pray. The Prophet (saw) was not satsified with any of these ideas. He waited to hear a better idea or to recieve guidance from Allah.

Umar bin al-Khattab (radiAllahu anhu) suggested sending someone to announce the prayer. Allah's Messenger (saw) then appointed Bilal ibn Rabah (ra) to call the people to prayer. But it seems through the study of hadith that the method was not satisfactory. Then Prophet Muhammad (saw) agreed to use a Naqoose (a conch).

After having ordered a bell to be made so that it could be struck to gather the people to prayer; on that same day a companion, Abdullah bin Zaid bin Abd Rabbihi visited the Prophet (saw) and said to him "I was sleeping when I saw a man in a green garment carrying a naqoose in his hands, and I said, Servant of Allah will you sell this to me?' When he said what I would do with it? I replied, that we would use it to call the people to prayer. He said 'Shall I not guide you to something better than that?' I replied, 'Certainly', so he told me to say :

'Allahu Akbar, Allahu Akbar, Allahu Akbar, Allahu Akbar, Ash hadu an la ilaha illal lah, ash hadu an la ilaha illal lah,
Ash hadu an-na Muhammadar resulul-lah, Ash hadu an-na Muhammadar rasulul-lah, hayya 'alas, salah, hayya 'alas salah,
hayya 'alal falah, hayya 'alal-falah Allahu Akbar; Allahu Akbar, La ilaha illal lah.'

After the Adhan the stranger kept quiet for a while and then said, When the congregation is ready you should say:

Allahu Akbar, Allahu Akbar, Ash hadu an la lilaha illal lah, Ash hadu an-na Muham-madar rasAlul-lah,
hayya 'alas salah, hayya 'alal falah, qad qama tis salah, qad qama tis salah,
Allahu Akbar, Allahu Akbar, la ilahillallah.

After listening to Abdullah bin Zaid, Allah's Messenger (saw) said, "It is a true vision, insha-Allah, so get up along with Bilal, and when you have taught him what you have seen let him use it in making the call to prayer, for he has a stronger voice than you have". When Bilal ibn Rabah (ra) had learnt the words, the Prophet (saw) asked him to climb a high wall next to the masjid and call people for Salah. Bilal did what the Prophet (saw) told him to do and so became the first Mu'adhdhin of Islam.

When Umar bin al-Khattab (ra) heard the adhan, he was in his house and came out trailing his cloak and said, 'Messenger of Allah (saw), by Him who has sent you with the truth, I have seen the same kind of thing as has been revealed.' To this Allah's Messenger (saw) replied, 'Praise be to Allah!'

Since that time until present day the adhan is said to gather people for the congregational prayer 5 times a day.

Translation:

Allahu Akbar Allah is the greatest
Allahu Akbar Allah is the greatest
Ash hadu an la ilaha illal lah I bear witness that there is no deity worthy of worship except Allah.
Ash hadu an la ilaha illal lah I bear witness that there is no deity worthy of worship except Allah.
Ash hadu an-na Muhammadar rasulul lah I bear witness that Muhammad(saw) is the messenger of Allah.
Ash hadu Anna Muhammadar rasulul lah I bear witness that Muhammad(saw) is the messenger of Allah.
Hayya 'alas salah Come to payer
Hayya 'alas salah Come to prayer.
Hayya 'alal falah Come to your success
liayya 'alal falah Come to your success.
Allahu Akbar Allah is the greatest
Allahu Akbar Allah is the greatest
La ilaha illal Lah There is no deity worthy of worship except Allah.

An additional phrase is included twice in the adhan for the Fajr prayer after the second 'Hayya 'alal Falah'
As salatu Khayrum minan nawm - Prayer is better than sleep.
As salatu Khayrum minan nawm- Prayer is better than sleep.