Why were chains of transmitters added to hadith reports after the first generations of Islam?

Chains of transmitters, known as the isnād, were developed and added to hadith reports primarily to address the challenge of verifying the authenticity of traditions attributed to the Prophet Muhammad.1

Following the death of Muhammad, the transmission of his traditions was initially informal and spontaneous. However, as these reports gained authority in shaping Islamic beliefs and legal practices, the community faced the rise of forged or falsely attributed reports created to support personal or political views. By the second century of Islamic history, the isnād became a standard literary form to combat this, serving as a mechanism to facilitate the verification of a report's pedigree.12

By listing the names of narrators in chronological order, scholars could scientifically scrutinize the reliability and orthodoxy of each transmitter in the chain. This system allowed scholars to differentiate between authentic and compromised traditions, ensuring that the sunnah—the example of the Prophet—remained a reliable foundation for Qur'ānic exegesis and fiqh (legal theory).12