Sliman Ben Ibrahim,
The Life of Mohammad, the Prophet of Allah
“ Passing one day near the Ramda, Abu Bakr witnessed this cruel sight. 'Fearest thou not the justice of Allah, the Most High, O Oummayatah! when thou dost inflict such torment on that wretched man?' he cried indignantly.—'Thou didst corrupt him; therefore 'tis thy duty to save him,' was the cynical reply.—'Willingly! I possess a young black slave, stronger and a better worker than thine. Moreover, he is entirely devoted to thy idols. I offer him to thee in exchange.' Oummayatah accepted and turned Bilal over to Abu Bakr who granted him his freedom straightway. ”
