Looking for some resources: The importance of the sunnah

:sl:
I dont know if this is in the right section...

Anyway as the title suggests, i am looking for lectures and books (in Arabic or English) discussing the importance of the sunnah. A good example of the type of source i am looking for, is along the line of Jamal ud-Deen Zarabozo's "The Authority and importance of the Sunnah."*

Specifically, i am looking for a source/s which address this type question:

What is the ruling of someone who rejects something from the sunnah even if that particular thing is not considered obligatory?

In light of the fact that it is from the sunnah yet someone rejects/denys that it is from the sunnah, what is the ruling on that. im not asking in respect to whether that particular thing maybe obligatory or not, but the simple fact that it is approved by and is a part of the sunnah and yet one rejects/deny's/claims that it isnt...what is the ruling on such


do let me know if the question doesnt make sense.

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*is this book available in Arabic?