Some men of the Ansar asked for the permission of Allah's Messenger (ﷺ) and said, "Allow us to give up the ransom from our nephew Al-`Abbas. The Prophet (ﷺ) said (to them), "Do not leave (even) a Dirham (of his ransom).
Sahih al-Bukhari Book 49, Hadith 21
← Previous Hadith I bought Barirah but her masters put the condition that her Wala' would be for them. I told the Prophet (ﷺ) about it. He said (to me), "Manumit (free) her as her Wala' will be for the one who pays the price." So, I manumitted (freed) her. The Prophet (ﷺ) called Barirah and gave her the option of either staying with her husband or leaving him. She said, "Even if he gave me so much money, I would not stay with him," and so she preferred her freedom to her husband.

Sahih al-Bukhari Book 49, Hadith 20 Next Hadith → My father told me that Hakim bin Hizam manumitted one-hundred slaves in the Pre-Islamic period of ignorance and slaughtered one-hundred camels (and distributed them in charity). When he embraced Islam he again slaughtered one-hundred camels and manumitted one-hundred slaves. Hakim said, "I asked Allah's Messenger (ﷺ), 'O Allah's Messenger (ﷺ)! What do you think about some good deeds I used to practice in the Pre-Islamic period of ignorance regarding them as deeds of righteousness?' Allah's Apostle said, "You have embraced Islam along with all those good deeds you did."

Sahih al-Bukhari Book 49, Hadith 22