Is the exemption from Jizyah (poll tax) claimable by People of the Covenant based on a document from the Prophet (peace be upon him)?

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The claim made by some People of the Covenant that the Jizyah is not obligatory for them because they possess a document from the Prophet, peace be upon him, exempting them is invalid. Abu al-Abbas Ibn Surayj was questioned about this and declared that no Muslim scholar has narrated such a claim. Furthermore, when they were challenged to produce evidence, they presented a document alleged to be in the handwriting of Ali, may Allah be pleased with him, written on behalf of the Messenger of Allah, peace be upon him. This document contained the testimony of Sa'd ibn Mu'adh and Mu'awiyah, and was dated after the death of Sa'd and before the conversion of Mu'awiyah to Islam. This internal contradiction proves its falsehood.