The Isnad, or chain of transmission, would be used to verify Hadiths and guarantee the authenticity of sacred knowledge. Muslims need not accept Hadiths blindly. In fact, they should not accept any instruction or claim uncritically. Rather, they only had to obey a Hadith if they found an Isnad demonstrating that it had been transmitted reliably from the Prophet. ‘The Isnad is part of the religion,’ proclaimed a Sunni contemporary of Shafi‘i. ‘If not for the Isnad, whoever wanted could say whatever they wanted.’
