Barira was a female slave before she got married to a black man whose name was Mugith ibn Jahsh. After Barira got her freedom back, she wanted to divorce her husband. For this she asked about her rights and decided to get divorced.
Mugith felt very sorry about this and roamed the streets of Madinah crying. He begged Muhammad to help him to be reunited with his wife. After this Muhammad tried to induce Barira to continue her marriage. Barira wanted to know if this was the Prophet’s order or not. When she realised she wasn’t forced to do this, she insisted on her decision and got divorced from her husband.
(Bukhari, Talaq 14-15 (26-28), At’imah 31, Faraid 20, 22; Muslim, Itk 9-14; Abu Davoud, Talaq 9/2231; Ibn Majah, Talak 29).