Sahih Bukhari Volume 3, Book 46, Hadith Number 699.

Narated By 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.