Abu Dawud Book 24, Hadith Number 3930.
Chapter : The view that a slave will not be required to work for purchasing his freedom.
Narated By N/A : The tradition mentioned above has also been transmitted by Ibn ‘Umar to the- same effect through a different chain of narrators. Nafi’ sometimes said: He will be emancipated to the extent of the share which he emancipated, and sometimes he did not say these words.