I heard Messenger of Allah ﷺ as saying: He who emancipates a believing slave. Allah will set free from Fire his every limb for every limb of his (slave's), even his private parts for his. (Using translation from Muslim 1509c)
سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ مَنْ أَعْتَقَ رَقَبَةً مُؤْمِنَةً أَعْتَقَ اللهُ بِكُلِّ عُضْوٍ مِنْهُ عُضْوًا مِنْهُ مِنَ النَّارِ حَتَّى يُعْتِقَ فَرْجَهُ بِفَرْجِهِ