Abandoning Ahl ul-Bid’ah [the people of innovation] & their associates.
Allah’s Messenger (salallahalayhiwasalaam) said, Whoever innovates or accommodates an innovator then upon him is the curse of Allah, His Angels, and the whole of mankind. (Bukhari & Muslim)
Qaadee Aboo Yalaa (d. 333H) said, There is consensus (Ijmaa) among the Sahaabah and the Taabieen as regards to dissociating and cutting off from the innovators (Hajarul-Mubtadi, p32)
Al-Baghawee (d.535H) said, And the Sahaabah, the Taabieen, their successors and the Scholars of the Sunnah passed away while they were upon this, united and unanimously agreed upon having enmity towards the People of Innovation and fleeing from them. (Sharhus-Sunnah: 1/227)
Al-Baghawee also said, & the Prophet (salallahalayhiwasalaam) has informed about the splitting of this Ummah and the appearance of desires and innovations within it. & he ruled that deliverance would be for the one who followed his Sunnah and the Sunnah of his Companions (may Allah be pleased with them all). Therefore it is necessary for the Muslim, when he sees a man engaging himself with anything from the desires and innovations, believing in them, or belittling anything from the Sunnah, that he flees from him, disowns him and leaves him dead or alive. So he does not give salaam to him when he meets him and nor does he respond to him if he salutes first until the person abandons his innovations and returns to the truth. (Sharhus-Sunnah: 1/224)
Ibn Qudaamah (d.620H) said, The Salaf used to forbid sitting with the people of Innovations. Looking into their books and listening to their words. (Al-Aadaabus-Shareeah: 1/263)
Ibn Abbaas (d.68H) said, INDEED THE MOST DETESTABLE OF THINGS TO ALLAH ARE THE INNOVATIONS (Bayhaqee in his Sunan).
Al-Hasan al-Basree (d.110H) said, DO NOT SIT WITH THE PEOPLE OF INNOVATION & DESIRES, NOR ARGUE WITH THEM, NOR LISTEN TO THEM (Reported by ad-Daarimee in his Sunan, & al-Laalikaaee).