What is the criterion for ruling that a Muslim is an innovator?

Question:
He says: Honorable Shaykh, may Allah grant you success. Regarding the author's (may Allah have mercy on him) statement, "visiting a Muslim who is not an innovator," I would like you to provide a criterion for the innovator; because I see some of the brothers ruling that certain people are innovators.

Answer:
The criterion for the innovator is as the Prophet (peace and blessings be upon him) explained: "Whoever does a deed for which we have no command from us, it is rejected." This is what requires research; the text of the hadith is explicit. So the innovator is the one who acts upon a bid'ah (religious innovation), and bid'ah is that for which there is no evidence from the Book of Allah or from the Sunnah of His Messenger, by which one seeks nearness to Allah. Bid'ah only occurs in religion, not in customs. Bid'ah is in religion; religion is complete and does not need anyone to add to it. So whoever adds to it is an innovator. Is it permissible for a person to introduce a bid'ah or to act upon a bid'ah introduced by another? Both of their deeds are rejected. Yes.