He would then say to him: "Renounce Islam or swelter and die."
Even under these afflictions, Bilal would exclaim: "Ahad" -The One (Allah). "Ahad" - The One (Allah).
He was whipped at night and with the cuts thus received, made to lie on the burning ground during the day to make him either give up Islam or to die a lingering death from the wounds. Abu Jahl, Umayyah and others, would take turns in torturing Sayyidina Bilal and get tired competing with one another in afflicting more and more painful punishment, but Sayyidina Bilal was steadfast. At last Sayyidina Abu Bakr bought his freedom and he became a free Muslim.
While Islam implicitly taught the oneness of Almighty Allah the Creator, the idolaters of Makkah believed in many gods and goddesses with minor godlings, therefore Sayyidina Bilal repeated: "Ahad (The One), Ahad (The One)."
This shows his love 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 Makkah would drag him in the streets, with his words "Ahad! Ahad!" ringing in their wake.
Look how Allah rewarded his steadfastness. He had the honour of becoming the moazzin of Nabi. He was always to remain with him at home and abroad to call out the Azaan for his Salaah. After the death of Nabi, it became very hard for him to continue his stay in Madinah where he would miss him at every step and in every corner.He therefore left Madinah, and decided to pass the rest of his life striving in the path of Allah. Once he saw Nabi in his dream saying to him:
"O, Bilal! How is it that you never visit me?"
As soon as he got up, he set out for Madinah. On reaching Madinah, Sayyidina Hasan and Sayyidina Husain, the grandsons of Nabi, requested him to call out the Azaan. He could not refuse them, for they were very dear to him. But as soon as the Azaan was called out, the people of Madinah cried openly out of their anguish at the memory of the happy old days of Nabi time. Even the womenfolk came out of their houses weeping. After a few days Sayyidina Bilal left Madinah and passed away in Damascus in 20 A.H.