He must perform wudhu.
If he is senile and doesn’t know people, doesn’t know Day from night and doesn’t know ruku from sujood, prayer is not obligatory upon him.

Sheikh my dad is old and blind and now has short memory so when doing wudu for salah can he just do tayamum on the wall because he does not remember where to wash when i have to remind him. And he makes mistakes in salah due to memory please give me answers on these issue.

Prayer | June 14, 2017 5:42 pm
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When saying the salaam at the end of the prayer, the worshipper intends three things: -To exit the prayer -To send salaams upon the recording angels -To send salaams upon his fellow-worshippers. So, if we are praying in congregation and I am the last person in the left side of the row, while saying tasleem to the left side where there is one, what should I intend?
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I want to ask that suppose if I missed one rakah of zuhr prayer in congregation then should i do rafayadain after second rakah of mine or second rakah of imam?