Sahih Bukhari Volume 3, Book 46, Hadith Number 701.

Narated By Ibn ‘Umar : The Prophet said, “He who manumits his share of a slave and has money sufficient to free the remaining portion of that slave’s price (justly estimated) then he should manumit him (by giving the rest of his price to the other co-owners).” Nafi’ added, “Otherwise the slave is partially free.” Aiyub is not sure whether the last statement was said by Nafi’ or it was a part of the Hadith.