In the courts of Al-Ma'mun, the seventh Abbasid caliph, Ali al-Ridha, the great grandson of Muhammad and prominent scholar (Imam) of his era, was questioned by the High Jewish Rabbi to prove through the Torah that both Jesus and Muhammad were prophets. Among his several proofs, the Imam references the Book of Isaiah, stating "Sha‘ya (Isaiah), the Prophet, said in the Torah concerning what you and your companions say: ‘I have seen two riders to whom (He) illuminated earth. One of them was on a donkey and the other was on a camel. Who is the rider of the donkey, and who is the rider of the camel?'" The Rabbi was unable to answer with certainty. Al-Ridha goes on to state that "As for the rider of the donkey, he is ‘Isa (Jesus); and as for the rider of the camel, he is Muhammad, may Allah bless him and his family. Do you deny that this (statement) is in the Torah?" The Rabbi responds "No, I do not deny it."