Sahih al-Bukhari Book 49, Hadith 5
The Prophet (ﷺ) said, "Whoever manumits a slave owned by two masters, should manumit him
completely (not partially) if he is rich after having its price evaluated."
We were ordered to free slaves at the time of lunar eclipses.
Allah's Messenger (ﷺ) said, "Whoever frees his share of a common slave and he has sufficient money to free him completely, should let its price be estimated by a just man and give his partners the price of their shares and manumit the slave; otherwise (i.e. if he has not sufficient money) he manumits the slave partially."