What is the ruling on Zawiyas?

Zawiyas can be small mosques, and their construction is permissible and rewarded, as the Prophet, peace and blessings be upon him, said: "Whoever builds a mosque for Allah, be it like a bird's nest or smaller, Allah will build for him a house in Paradise."

They may also be places used by some Sufi orders for worship. If they are extremists who resort to other than Allah for supplication and seeking help, this is major shirk (polytheism), and it is not permissible to pray behind them or to sit with them. They must be advised and warned against if they do not desist. If they adhere to innovated litanies, then one must beware of their innovations. It is not permissible to build such places unless it is confirmed that they are not built to promote innovations or shirk.