One interesting example is that of Job ben Solomon or Ayuba Suleiman Diallo, which was his actual name. I have previously written about Diallo for the AskHistorians Tumblr, which I will reproduce here:

Ayuba Suleiman Diallo was a Fulbe Muslim, born in Senegal in 1701, who was ironically captured and sold as a slave when he was trying to do the same thing for his father in 1730. Diallo crossed the Atlantic on the ship Arabella and found himself working on a tobacco plantation in Maryland where he would work as a slave for the next two years. Escaping the plantation, Diallo was imprisoned since he could not identify who he was. While in prison, he met attorney Thomas Bluett, who saw him for what he really was: a literate man, who could both speak and write Arabic well.

Thomas Bluett himself wrote about his first impressions:

"He was brought into the Tavern to us, but could not speak one Word of English. Upon our Talking and making Signs to him, he wrote a Line or two before us, and when he read it, pronounced the Words Allah and Mahommed; by which, and his refusing a Glass of Wine we offered him, we perceived he was a Mahometan [Muslim], but could not imagine of what Country he was or how he got thither; for by his affable Carriage and the easy Composure of his Countenance, we could perceive he was no common Slave."

While Diallo had to return to his life of slavery, Bluett helped him to regain his freedom together with other individuals who felt compassionate about his situation. His master, eager to get rid of him since he saw no place for Diallo at the plantation after what had been known about him, sold his freedom willingly and Diallo was finally emancipated in England which he had traveled to together with Bluett in 1733. While in England, Diallo even got the opportunity to meet the Queen of England who according to Bluett presented him with a "rich Gold Watch". Diallo would return home to Senegal through Gambia a year later in 1734. Bluett published Diallo's story (and his own) in Some Memories of the Life of Job, the Son of the Solomon High Priest of Boonda in Africa; Who was enslaved about two Years in Maryland; and afterwards being brought to England, was set free, and sent to his native Land in the Year 1734 which is considered one of the earliest slave narratives of the Atlantic slave trade.

This portrait was painted by William Hoare of Bath in 1733 during Diallo's stay in England. He is depicted wearing the Qu'ran strung from his neck. The portrait can now be seen in the National Portrait Gallery in London.