A sahih hadith is a narration about the sayings, actions, or approvals of the Prophet Muhammad that is considered authentic and reliable. Scholars evaluate hadiths based on their chain of transmission and the integrity of the narrators. A sahih hadith must have a continuous chain of trustworthy narrators and be free from any defects. These hadiths play a crucial role in understanding Islamic teachings and law, as they provide context and clarification for the Qur'an. They are used by scholars to derive rulings and guide the behavior of Muslims in their daily lives.