Isma'il bin Abi Hakim (may Allah have mercy on him) said that Umar bin Abd al-Aziz (may Allah have mercy on him) freed a Christian slave. He died, and Isma'il (may Allah have mercy on him) said: Umar bin Abd al-Aziz (may Allah have mercy on him) ordered me to take his inheritance and deposit it in the public treasury (bayt al-mal).
(8) Chapter: "Whoever frees his slave as a sa'ibah"
Imam al-Shafi'i (may Allah have mercy on him) said: "So the emancipation takes effect, and his wala' belongs to him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الولاء / 21471