Al-Maqburi (may Allah have mercy on him) said that Sayyiduna Abu Hurayrah (may Allah be pleased with him) was asked about a man who is obliged to free a slave: may he free a child born of fornication? Sayyiduna Abu Hurayrah (may Allah be pleased with him) said: Yes.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 19998
Nafi' (may Allah have mercy on him) said that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) freed a child born of fornication (walad al-zina) and his mother.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 19999
Umm Hakim bint Tariq narrates from Sayyidah Aishah (may Allah be pleased with her) that concerning children born of fornication the ruling is: "Free them and treat them well."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 20000
Umar bin Abd al-Rahman al-Qurashi narrates from Sayyiduna Ibn Abbas (may Allah be pleased with them both) that he was asked about (freeing) a child born of fornication, and also about freeing a child of legitimate birth. He said: Look! Which of the two has the higher price? So they looked, and the price of the child born of fornication was higher by one dinar, so he ordered them (to free) him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 20001
It is narrated from al-Hasan (may Allah have mercy on him) that he said concerning the child born of fornication that freeing him and others is the same.
(b) Firas narrates from al-Sha'bi (may Allah have mercy on him): Whichever of them is higher in price.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 20002
Nafi' narrates from Sayyiduna Ibn Umar (may Allah be pleased with them both) that he freed a child born of fornication and said: "Allah and His Messenger (peace and blessings be upon him) have ordered us to show kindness to evil people." Allah Almighty says: "Then either (show) favour afterwards or (take) ransom." [Surah Muhammad: 4] It is narrated from Sayyiduna Umar (may Allah be pleased with him) that he disliked it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 20004
Abu Hasan, the freed slave of Abdullah bin al-Harith, who was among the early freed slaves of Quraysh and among their people of knowledge and righteousness, heard a woman saying to Abdullah bin Nawfal: I am obliged to free a slave; tell me about this. Abdullah bin Nawfal said: "You will not be discharged of the obligation by freeing a child born of fornication." Ibn Nawfal said: I heard Sayyiduna Umar (may Allah be pleased with him) saying: "That I give a pair of sandals in the path of Allah is dearer to me than that I free a child born of fornication."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأيمان / 20005