Hadhrat Bilal (RodiyallahAnhu) he's one of the best known amongst the galaxy of Sahaba as the muazin of the Prophet (Salla Llah Alei Wasalam)'s masjid.
He was an abyssinian slave of a disbeliever in makkah. His conversion to Islam was naturally not liked by his master, and he was therefore persecuted mercilessly. Ummaymah bin Khalaf who was the worst enemy of Islam would make him lie down on burning sandat midday and would place a heavy stone on his breast, so that he could not even move a limb. He would then say to him:
Renounce Islam or swelter and die.
Under these afflictions Bilal (Rodiyallah Anhu) would exclaim;
Ahad! The one Allah! Ahad!
He was whipped at night and with the cuts this received. Made to lie on burning ground during the day to make him either forsake Islam or to die a lingering death from wounds. The torturers would get tired and take turns (Abu(ahl), Umayyah and others) and vie with one another in afflicting more and more painful punishment,but Hadhrat Bilal (Rodiyallah Anhu) would not yield at last Abu Bakr (Rodiyallah Anhu) bought his freedom, and he became a free Muslim.
As Islam taught implicitly the oneness of Allah, while the idolaters of Mecca believed in many gods and goddesses with minor godling, therefore Bilal (Rodiyallah Anhu) repeated. Ahad (the one). Ahad (the one)." This shows his live and devotion to Allah. Allah was so dear to him that no amount of persecution could distract him from reciting His Holy name. It is said that the urchins of Mecca would drag him in his streets, with his words "Ahad!,Ahad! " ringing in their wake. Look how Allah rewarded his steadfastness! He was to have the honour of becoming the Prophet's Muazzin. He was always to remain with him at home and abroad to call out Azan of the Salah. After the Prophet's dead it became very hard for him to continue his stay in Madinnah where he would miss him at every step and in every corner. He therefore Madinah and decided to pass the rest of his life striving in the path of Allah. Once he beheld the Prophet (Sallah Llah Alei Wasalam) in his dream saying to him:
"O Bilal! How is it that you never visit me."
No sooner did he get up than he set out for Madinah. On reaching there. Hadhrat Hasan and Hadhrat Husain (Radiyallah Anhuma) the Prophet (Sallah Llah Alei Wasalam) grandsons requested him to call out Azan. He could not refuse them, for they were very dear to him. But as soon as the Azan was called. The people of Madinah cried openly out of their anguish at the memory of the happy days of the Prophet's (Sallah Llah Alei Wasalam) time. Even when the woman came out of their houses weeping. Hadhrat Bilal (Rodiyallah Anhu) left Madinah again after a few days and died in Damascus in 20 A.H.
All Praise is due to Allah we ask Him to let us die on the path of Qur'an and Sunnah.