The Prophet ﷺ said, "If somebody manumits a Muslim slave, Allah will save from the Fire every part of his body for freeing the corresponding parts of the slave's body, even his private parts will be saved from the Fire) because of freeing the slave's private parts."  

عَنِ النَّبِيِّ ﷺ قَالَ مَنْ أَعْتَقَ رَقَبَةً مُسْلِمَةً أَعْتَقَ اللَّهُ بِكُلِّ عُضْوٍ مِنْهُ عُضْوًا مِنَ النَّارِ حَتَّى فَرْجَهُ بِفَرْجِهِ