Isnad is a term used in Islamic scholarship to refer to the chain of narrators who transmit a particular saying or action of the Prophet Muhammad. It is a critical component of hadith literature, as it helps establish the authenticity and reliability of the reported information. Each narrator in the chain is evaluated for their character and memory to ensure the integrity of the hadith. The process of verifying an isnad involves examining the biographies of the narrators, known as ilm al-rijal, and assessing their connections to one another. A strong isnad indicates a trustworthy transmission, while a weak or broken chain raises doubts about the hadith's credibility.