Tuhia he haere tonu mo tenei waahanga - Ko Abu l-Abbas al-Fadl ibn Sahl ibn Zadhanfarukh al-Sarakhsi (; i mate i te tau 818), i tapaina ko Dhu 'l-Ri'āsatayn ("te tangata o nga upoko e rua"), he perehi rongonui o te wa o Abbasid i Khurasan, i mahi i raro i te Caliph al-Ma'mun (r. 813 <unk> 832). He tūranga nui tana i roto i te pakanga ā-iwi
i waenganui i al-Ma'mun me tona teina al-Amin (r. 809 <unk> 813), a ko ia te vizier o te Abbasid Caliphate tae noa ki te 817.