Concept:Hadith 9 of an-Nawawi teaches believers to avoid unnecessary and excessive questioning in matters of religion.Explanation:This hadith warns against asking too many questions that may lead to hardship or confusion.It advises Muslims to follow clear guidance without overburdening themselves.Excessive questioning was discouraged because it could create difficulties in practice.Therefore, the admonition in Hadith 9 is specifically against excessive questioning.Answer:D. Excessive questioning