The Polytheists Persecute the Muslims of the Lower Classes

Then the Quraysh showed their enmity to all those who followed the apostle; every clan which contained Muslims attacked them, imprisoning them, and beating them, allowing them no food or drink, and exposing them to the burning heat of Mecca, so as to seduce them from their religion. Some gave way under the pressure of persecution, and others resisted them, being protected by God.

Bilâl, who was afterwards freed by Abû Bakr but at that time belonged to one of B. JumaH, being slave born, was a faithful Muslim, pure of heart. His father's name was RibâH and his mother was Hamâma. Umayya b. Khalaf b. Wahb b. Hudhâfa b. JumaH used to bring him out at the hottest part of the day and throw him on his back in the open valley and have a great rock put on his chest; then he would say to him: ‘You will stay here till you die or deny Muhammad and worship Al-Lât and Al-`Uzzâ.’ He used to say while he was enduring this, ‘One, one!’

Hishâm b. `Urwa told me on the authority of his father: Waraqa b. Naufal was passing him, while he was being thus tortured and saying, ‘One, one’, and he said, ‘One, one, by God, Bilâl.’ Then he went to Umayya and those of B. JumaH who had thus maltreated him, and said: ‘I swear by God that if you kill him in this way,  I will make his tomb a shrine.’ One day Abû Bakr passed by while they were thus ill-treating, for his house was among this clan. He said to Umayya, ‘Have you no fear God that you treat this poor fellow like this? How long is it to go on?’ He replied, ‘You are the one who corrupted him, so save him from his plight that you see!’ ‘I will do so,’ said Abû Bakr, ‘I have got a black slave, tougher and stronger than he, who is a heathen. I will exchange him for Bilâl.’ The transaction was carried out, and Abû Bakr took him and freed him."
 

(Alfred Guillaume, The Life of Muhammad, Karachi-Oxford-New York-Delhi 1978, page 143 f., the transliteration of Arabic names has been adapted)