Concept:Hadith 3 of an-Nawawi teaches Muslims to control anger and avoid its harmful effects.Explanation:A man once asked the Prophet Muhammad (SAW) for advice.The Prophet (SAW) replied, “Do not become angry,” and repeated this instruction.This shows that anger can lead a person into sin and regret.Islam encourages patience, calmness, and self-control when provoked.Therefore, the hadith focuses on the effect of anger on human behaviour.Answer:C. Effect of anger.