Those who said: a slave's bequest stands where he assigns it

Hisham narrated that al-Hasan and Muhammad bin Sirin said: A man's will takes effect where he has made it, unless the person responsible for the will comes under suspicion.

It is narrated from Jabir that Amir said: The person responsible for a will holds the rank of a father; and when he comes under suspicion, he should be removed, or another man should be joined with him.