 Al @-@ Tabari states that al @-@ Mu 'tasim fell ill on 21 October 841 . His regular doctor , Salmawayh ibn Bunan , whom the Caliph had trusted implicitly , had died the previous year and the new physician Yahya ibn Masawayh did not follow the normal treatment of cupping and purging , which according to Hunayn ibn Ishaq worsened the caliph 's illness and brought about his death on 5 January 842 , after a reign of eight years , eight months and two days according to the Islamic calendar . He was buried in the Jawsaq Palace in Samarra . He was succeeded by his son , al @-@ Wathiq . 
