I recently began attending a new Masjid and I observed them performing a specific Dhikr in congregation after every Salah. They claim a Sheikh instructed them to do so to protect the Masjid. I informed them, according to my knowledge their actions were not permissible for many reasons. Am I correct; is there such a Dhikr? Should it be done collectively?
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If by congregational Thikr you mean repeating a form of Thikr (e.g. Subhana Allah, Allahu Akbar) in group, then this is not reported from the Prophet nor his Companions. For sure, if it was good, they (companions) would not neglect it; if they did it, it would be reported to us since even their hidden acts were reported to us. Thus, such an action is an innovation and every innovation is a misguidance.
We don't know of any Islamic form of Thikr to protect the mosque. All forms of worship are to be followed as taught by the infallible Prophet and not by any other person.
Therefore, you have to avoid such a way of Thikr and advise your friends to do so. Also, you have to adhere to the confirmed way and forms of Thikr that are reported in the Sunnah.
You will find in the Sunnah so many different forms of Thikr that are to be repeated individually after prayers and on some fixed or free occasions. The Sunnah is full of such forms that are sufficient to help one avoid circulating innovations.
We advise you to refer to the book entitled al-I’tisaam by ash-Shatibi.
For more benefit that congregational Thikr after prayer is an innovation, please refer to Fatwa 227410.
Allah knows best.
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