Based on obligatory precaution, a person who has a legitimate excuse [for performing prayers in a certain way] – for example, he performs prayers with tayammum or in a sitting position – cannot be hired in any case to perform the prayers of a deceased person, even if the prayers of the deceased became qaḍāʾ in the same way. However, hiring someone who performs prayers with jabīrah wuḍūʾ or with jabīrah ghusl is not a problem.
The same applies to hiring someone whose hands or feet have been amputated, although to suffice with the acts he performs on behalf of the person is problematic [i.e. based on obligatory precaution, one must not suffice with the acts he performs].