Kunyora kuenderera kweiyi ndima - Mushure mekufa kwaHaruni muKhurasani mukutanga kwa809, Abdallah akasara mudunhu, achijoinha dare remugari wenhaka wechipiri waHaruni, al-Ma'mun (r. 813-833), paMarw. Muhondo yevagari vemo yakatevera
pakati pa al-Ma'mun nehanzvadzi yake, Caliph al-Amin (r. 809<unk>813), akaramba ari parutivi paMarw. Akanga ari mumwe wevatungamiri vemauto vakaramba kutungamira hurumende yaAl-Ma'mun, chinzvimbo chakazopedzisira chawira kuna Fadl ibn Sahl. Ukama hwake naal-Ma'mun hwakanga husina kunaka, asi akaenda naye kumadokero uye akanga ainaye paakapinda muBaghdad muna 819.