From Sahih Muslim (Hadith 4326):
Ibn 'Umar reported Allah's Messenger (ﷺ) as saying:He who emancipates his share in the slave, it is his responsibility to secure full freedom for him provided he (the slave) has enough money to pay the (remaining) price, but it he has not so much money he would be emancipated to the extent that the first man emancipated
Reference: Muslim 4326