Bilal Habashi (r.a.)
Bilal was an Abyssinian slave. He was a slave of Umayya bin Khalaf. Bilal was looking for a high truth. What he was looking for was nothing but Islam. When the Prophet started to spread the religion of Islam, Bilal Habashi became one of the first Muslims. He met the eternal need of his soul with Islam. From time to time, he went to the Messenger of Allah to listen to his blessed talk without disrupting the work of his master. His master, Umayya bin Khalaf, was against Islam. He would never allow Bilal to become a Muslim. When he heard that Bilal had become a Muslim, he went crazy. He resorted to all kinds of pressures to dissuade him from his new religion. He applied unimaginable tortures. He tied his hands and feet, putting him on the hot sand; then, he put big stones on his stomach. He left Bilal like that for days without giving him food and water. He said, "If you do not deny Muhammad and if you do not worship our idols, you will remain like this until you die."
If Bilal had abandoned his religion and if he had spoken against the Prophet, all of the tortures would have ended and he would even have been freed. However, Hz. Bilal, the hero of patience, did not surrender to this cruel master. He never fulfilled his wished. He said "Allah," and "the Prophet." He did not forget Allah even for a moment even when he groaned due to the severity of the tortures. He always expressed the unity of Allah aloud by saying, "Ahad, Ahad (One, One)!" Umayya, the ferocious polytheist, did not regard these tortures enough. He increased his cruelty. He put a rope around Bilal's neck and gave him to the hands of the mad people of Makkah. They took him to the mountains around Makkah and tortured him. Umayya thought he was going to overcome his belief with force, but he was wrong. Bilal's faith increased. As he increased the severity of the tortures, Bilal always said, "Ahad, Ahad!"
These tortures were of no significance in the eye of Bilal. What distressed him was to remain away from the Messenger of Allah, for whom he wanted to sacrifice his life. He could not put up with the longing for the Prophet. 
One day, while he was under such torture, Hz. Abu Bakr passed by. He became very sad when he saw Bilal's agonies. He could not help saying, "Umayya! Fear Allah! How long will you continue this cruelty?" In a shameless and insolent manner, Umayya said, "You deceived him. You alienated him from our idols! If you feel pity for him, come and save him."
Hz. Abu Bakr thought for a while. Then he said, "Of course, I will save him. I have a non-Muslim slave. If you want, we can exchange them. Besides, he is stronger than Bilal." After a long bargaining, Umayya finally accepted his offer. Thus, Hz. Abu saved Bilal from these tortures and freed him for Allah.
After thanking Abu Bakr, who freed him, Bilal said to him,
"If you have freed me for the sake of Allah, let me go so that I will work in the way of Allah. If you have done this favor to make me your servant, show me where I will work so that I will work."
Hz. Abu Bakr, who was moved by these words, said,
"Yes, I have freed you only for Allah's sake. It is for Allah's sake. It is enough for me if I attain His consent." 
The Messenger of Allah and the Companions were discussing about how to call the believers to prayer. Finally, upon a dream seen by several Companions, the present form of was adopted. And the duty to call adhan was given to Bilal. The call to prayer we hear five times a day was first read by Bilal. The adhan of Muhammad called by Bilal with a touching voice early in the morning left deep traces in the hearts. A woman from Sons of Najjar narrates a memory related to Bilal's adhan as follows:
"Our house was the highest one around the mosque. Bilal came here early every morning, waiting for the dawn to break. When the dawn broke, he would call adhan."
With his adhan, the believers would flock to the mosque to pray. Bilal always called adhan from the day it was ordered to the death of the Messenger of Allah.
One of the things that Bilal loved the most was when the Messenger of Allah said to him, "O Bilal! Get up and call adhan!" The Messenger of Allah expressed his love for Bilal by saying, "Lucky is Bilal! He is the master of muezzins." Bilal has always been remembered as "Sayyid al-Muezzinin (Master of Muezzins)" in the history of Islam.
That the Prophet gave Bilal the duty of calling adhan infuriated the enemies of Islam. Someone who used to be their slave started to call people to Allah by adhan openly. After the conquest of Makkah, when Hz. Bilal called adhan on the Kaaba, the ferocious enemies of Islam showed their insolence by saying, "Did Muhammad not find anyone else other than this black crow to call adhan?" They could not accept it when they saw that the poor gained such honor and were elevated by Islam. They even said to the Prophet, “If you drive the poor and lonely people like Bilal away, we will believe in you. We cannot be equal to them."
Hz. Bilal, who attained the love of the Messenger of Allah and his blessed praise against the grudge and hatred of the enemies of Islam, did not mind the words of the polytheists. The pleasure of belief and the love of the Messenger of Allah were his source of happiness. He did not have any wealth. He was usually hungry like the Prophet (pbuh). His heart and spirit were in peace and tranquility. He reflected this pleasure in the adhans he called.
One day, the Messenger of Allah said to Hz. Bilal, "O Bilal! On the night of Miraj, I heard footsteps at the back while I was entering Paradise with Jibril. I asked Jibril, 'Whose footsteps are these?' Jibril said to me, 'Bilal'. What good things do you do to attain such a high rank?" Hz. Bilal said,
"O Messenger of Allah! I fulfill the fard deeds. And I always try to have wudu."
These were some of the characteristics that elevated the spiritual rank of Hz. Bilal: To fulfill the fard deeds, to avoid harams and try to have wudu, which is the spiritual weapon of believers.
The Prophet’s praise and compliments about Bilal did not cause him to feel conceited. He was always in modesty and humbleness. When he was reminded of his virtues and Prophet’s praise and compliments he would say, "Was I not an Abyssinian slave yesterday?" Allah Almighty elevated his spiritual rank because of his humbleness. He made him a neighbor of the Messenger of Allah in Paradise.
Hz. Bilal took part in many battles with the Messenger of Allah such as Badr, Khandaq and Uhud. He made jihad to elevate the word of Allah.
The death of the Messenger of Allah opened a deep wound in his spirit. He could not stay in Madinah any longer. For, the mountains of Madinah reminded him of the Messenger of Allah. Hz. Abu Bakr insisted that he should stay, but he could not convince him. Hz. Bilal went to Damascus. He made all mujahids cry with the adahn he called when Hz. Umar arrived in Damascus.
Upon a dream he saw in Damascus, he visited Madinah. He saw Hasan and Husayn next to the grave of the Messenger of Allah. He recollected his memories. He had not called adhan in Madinah after the death of the Messenger of Allah. He could not call adhan after that great Prophet left this ephemeral world. He was so accustomed to receive the order "O Bilal! Get up and call adhan!" from the Messenger of Allah that he could not call adhan after his death. However, he finally he decided to call adhan once again in Madinah. The mountains and stones in Madinah remembered the Messenger of Allah when Bilal started to call adhan for the morning prayer. The streets became full of human beings. Everybody was outside. They recalled the Era of the Messenger of Allah and they were crying. It sounded as if the Messenger of Allah got up and made Bilal call adhan. There was not a single person who did not cry in Madinah that day. Everyone fulfilled their longing for the Messenger of Allah to a certain extent.
Hz. Bilal returned to Damascus. He passed away in Damascus in 20 H.
May Allah be pleased with him!
 Usdul-Ghaba, 1: 206; Tabaqat, 3: 232; Hayatus-Sahaba, 1: 208-9.
 Hilya, 1:150; Usdul-Ghaba, 1:208.