Concept:Hadith 15 teaches Muslims to control their speech and say only what is good.
Explanation:The phrase "Falyaqul Khayram awliyasmul" means "Let him speak good or keep silent."
This instruction appears in Hadith 15 of Imam an-Nawawi's collection.
The Prophet connects this advice with faith in Allah and the Last Day.
A Muslim should not speak harmful, false, or useless words.
If a person cannot make a decent utterance, then silence is better.
Thus, the hadith directly promotes decent speech, not merely action or effort.
It discourages gossip, insults, lies, and careless talk.
It encourages words that are useful, truthful, and respectful.
Answer:D. Decent utterance