Is a bequest (Wasiyyah) valid when the appointed executor is incapable due to illness or weakness?

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The bequest remains valid when the appointed executor is incapable of managing affairs due to an ailment or weakness. The judge (Hakim) must appoint a trustworthy custodian to assist the executor. The executor's authority (Wilayah) and oversight over the wealth are not removed because the weak person remains eligible for executorship and trustworthiness. This is the position held by Al-Shafi'i and Abu Yusuf, and there is no known disagreement against this view.