The praise is for Allaah, and may peace and salutations be upon the Messenger of Allaah, upon his Family and his Companions. To proceed:
One leaves from the Sunnah by taking to an innovation from amongst the innovations, regardless of whether it is the innovation of khurooj (revolt), such as the Khawaarij, or the innovation of ta’teel (denial) of the Attributes (of Allaah), such as the Jahmiyyah and the Mu’tazilah, or ta‘weel (figurative interpretation) of them, such as the Ashaa’irah, or if he says that sins do not harm one’s Islaam, such as the Murji‘ah, or other than that from amongst the innovations. So if you know of an innovation from him, then advise him about it, but if he persists in remaining upon it, then he is to be considered one who has left the Sunnah and taken to the innovation. Indeed, Muslim (d.261H) related in the introduction to his book that Abaa ’Abdur-Rahmaan as-Sulamee advised some of the students of knowledge in that time that they must not listen to the statement of Shaqeeq. And Shaqeeq was not Shaqeeq Ibn Salamah. And he held the view of the Khawaarij. So he (Aboo ’Abdur-Rahmaan as-Sulamee) said that they must not listen to his speech and that they must not go to him. So the apparent meaning of this is that the one whose affair has settled upon taking to an innovation and he has become known for that innovation, then it is befitting that the students of knowledge be advised against him and that they be warned against him. This is because he is considered one who has left the manhaj of Ahlus-Sunnah due to that. As for when the opposition occurs in the subsidiary affairs of ijtihaad (independent reasoning), then this is not considered prohibited opposition and it does not obligate rebuke upon the opponent. It is like the one who says, “Indeed, adultery cannot be confirmed, except by a confession made four times.” And someone else says, “Indeed, it is confirmed by one confession.” And the success lies with Allaah.