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Musa al-Kazim was a Shi'a imam. He died in 799 AD, and it is believed that he was poisoned by the Abbasid caliph Harun al-Rashid. Harun al-Rashid wanted to prevent Musa al-Kazim from becoming the imam, and he believed that poisoning Musa al-Kazim would be the best way to achieve this goal. Musa al-Kazim's death was a major event in Shi'a history, and it is still remembered today.