Sahih Bukhari
Manumission of Slaves
Volume: 003 / Book Number: 046 / Hadith Number: 699
Narrated Ibn 'Umar:
Allah's Apostle said, "Whoever manumits his share of a slave, then it is essential for him to get that slave manumitted' completely as long as he has the money to do so. If he has not sufficient money to pay the price of the other shares (after the price of the slave is evaluated justly), the manumitted manumits the slave partially in proportion to his share.