It is reported that Al-Fuḍayl b. ʿAyyāḍ – Allāh have mercy on him – said:

Verily, Allāh has angels who seek out the circles of remembrance [of Allāh], so be careful who you sit with; make sure it is not with an adherent of bid’ah, for Allāh does not look at them. And the sign of nifāq (hypocrisy in faith) is that a man mingles with an adherent of bid’ah.

Ibn Battah, Al-Ibānah Al-Kubrā 1:460