Muwatta Imam Malik (Riwayat Yahya)

Imam Malik, may Allah have mercy on him, said that when a man forgives his mukatab (contracted slave) a thousand dirhams either at the beginning or at the end of the contract, and the total amount of the contract is three thousand dirhams, then the value of the mukatab will be assessed, and then this value will be divided for each thousand. The value of the thousand whose term is shorter will be less compared to the thousand that comes after it. Similarly, the thousand that is at the very end will have the least value, because as the term increases, the value decreases accordingly. Then, the value that falls upon the thousand which has been forgiven will be deducted from the one-third of the wealth. If it is less or more than that, it will also be according to this calculation.