Imām al-Subkī expressed this point most eloquently when discussing a follower of a legal school who encounters a hadith that his school has not adopted and knows of no scholar outside his school who has acted on it:

“The safest course, in my view, is to follow the hadith itself. Let a person picture himself standing before the Prophet ﷺ, having just heard that very statement from him—could he possibly delay putting it into practice? By Allah, he could not! Every individual is responsible in proportion to his understanding.1”

I say: This supports what we have already said—namely, that their error stems from doubting the Sunnah’s authenticity. Had they been certain that the Messenger of Allah ﷺ had actually said the words in question, they would never have voiced those principles, much less applied them to oppose hundreds of authentic reports from the Prophet ﷺ. Their only grounds are personal opinion, analogy (qiyās), and the practice of a particular group, as we noted earlier. Sound practice is restricted to what agrees with the Sunnah; adding to it is an unwarranted addition to the religion, and subtracting from it is a deficiency in the religion. Ibn al-Qayyim (1/299), explaining these two notions of addition and subtraction, said:

“The first is analogy, and the second is invalid specification; both lie outside the religion. Whoever does not halt at the texts will at times add to them what they do not contain and say, ‘This is analogy,’ at other times he will remove from them part of what they entail, take the ruling out of its scope, and say, ‘This is specification.’ At still other times he will abandon the text altogether and say, ‘No one acts upon it,’ or, ‘It goes against analogy,’ or, ‘It conflicts with the foundational principles.’” He said: “And we see that whenever a man plunges…"