Is it permissible to pay a sum of money as an alternative to fasting for the expiation of accidental killing, and what is the required amount to be paid if that is possible?

The expiation for unintentional killing is the freeing of a believing slave. If one cannot find [a slave], then one must fast for two consecutive months. The fasting is not immediate; it can be done at a later time if it becomes difficult for him.

Scholars have differed concerning one who is completely unable to fast: does the fasting obligation drop from him with nothing further required, or should he feed sixty poor persons by analogy with ẓihār? Some contemporary scholars permit paying one-tenth of the blood money instead of freeing [a slave], but this was not reported from the predecessors.