Ibn Majah: Hadith 2080

Three Sunan were established because of Barirah: She was given the choice (of whether to remain married) when she was freed, and her husband was a slave; they used to give her charity and she used to give it as a gift to the Prophet (ﷺ), and he would say: 'It is charity for her and a gift for us,' and he said, the 'Wala' is for the one who set the slave free.'"