Concept: Hadith 5 of an-Nawawi teaches that any new practice introduced into Islam which is not part of it is rejected.
Explanation:Hadith 5 is reported by Aisha (may Allah be pleased with her).
The Prophet (peace be upon him) said that whoever innovates something in this matter of ours (Islam) that is not from it, it will be rejected.
This means acts like adding new religious practices or beliefs without Quranic or Prophetic basis are unacceptable.
Therefore, the main reason Muslims should pay attention to this hadith is that it discourages innovations in religion.
It does not primarily deal with backbiting, excessive questioning, or sincerity.
Answer: A. discourages innovations in religion