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al-Hadi was the third Abbasid caliph in the mid-8th century, also known as Abu Muhammad Musa al-Hadi. His father was al-Mahdi, the second Abbasid caliph, who reigned from 775 to 785. al-Hadi's grandfather was the first Abbasid caliph, Abdullah al-Saffah. al-Hadi ruled briefly for one year from 785 to 786 before his untimely death, making his brother Harun al-Rashid the next caliph.