In the Name of Allah, the Gracious, the Merciful
Imam al-Nawawi records in his book Meadows of the Righteous:
باب فضل العتق
Chapter on the virtue of emancipating slaves.
Source: Riyāḍ al-Ṣāliḥīn 1/376
Allah Almighty said:
فَلَا اقْتَحَمَ الْعَقَبَةَ وَمَا أَدْرَاكَ مَا الْعَقَبَةُ فَكُّ رَقَبَةٍ
If only they had attempted the challenging path of goodness instead! And what will make you realize what attempting the challenging path is? It is to free a slave.
Surat al-Balad 90:11-13
Abu Huraira reported: The Prophet, peace and blessings be upon him, said:
مَنْ أَعْتَقَ رَقَبَةً مُسْلِمَةً أَعْتَقَ اللَّهُ بِكُلِّ عُضْوٍ مِنْهُ عُضْوًا مِنْ النَّارِ حَتَّى فَرْجَهُ بِفَرْجِهِ
Whoever frees a Muslim slave, then Allah will free every limb of his body from the Hellfire, even his private parts.
Source: Ṣaḥīḥ Muslim 1509, Grade: Sahih
Abu Dharr reported: I said, “O Messenger of Allah, which deed is best?” The Messenger of Allah, peace and blessings be upon him, said:
الْإِيمَانُ بِاللَّهِ وَالْجِهَادُ فِي سَبِيلِهِ
Faith in Allah and jihad in His way.
I said, “Which slave is the best to free?” He said:
أَنْفَسُهَا عِنْدَ أَهْلِهَا وَأَكْثَرُهَا ثَمَنًا
One who is valuable to his master and whose price is high.
Source: Ṣaḥīḥ al-Bukhārī 2518, Grade: Muttafaqun Alayhi
Abu Musa al-Asha’ri reported: The Prophet, peace and blessings be upon him, said:
أَطْعِمُوا الْجَائِعَ وَعُودُوا الْمَرِيضَ وَفُكُّوا الْعَانِيَ
Feed the hungry, visit the sick, and set the captives free.
Source: Sahih Bukhari 5058, Grade: Sahih
Success comes from Allah, and Allah knows best.