If a Masjid is under the control of the Sufiyyah or other than them from the people of innovation. Is helping them in cleaning that masjid or other than that from what leads to increasing their strength?
What is appropriate is that the People of Sunnah build a masjid specific for them where they can be independent and pray in it. And they do not need to pray behind the people of innovation.
[Sharh Tirmidhi no.82]
Faisal Ibn Abdul Qaadir Ibn Hassan