Tuhia he haere tonu mo tenei waahanga - I tiimata a Fadl i tana mahi i te kingitanga o Harun al-Rashid (r. 786 <unk> 809) hei kaitiaki mo Harthama ibn A'yan, i taua wa ko ia te rangatira o te kaitiaki o te kaaripa. Na tana pukenga whakahaere i aro atu ai ia ki a Harun, nana nei ia i whakatu hei kaituhituhi i te "diwan al-kharaj" (te "Puka o te Taake Whenua"). I te wā o te pakanga ā-iwi
I muri i te matenga o Harun, ka hoki a Fadl ki ona whenua i Iraq. I reira ia i tae mai ai ki te aro o Abu Ishaq, te teina o Caliph al-Ma'mun (r. 813 <unk> 833) me te Caliph al-Mu'tasim o muri mai, nana nei i aro nui ki tana mohio mo te taake me te ahuwhenua. I te tau 828, i mauria ia e Abu Ishaq ki Ihipa, katahi ka tohua ia hei upoko mo te "diwan al-kharaj".