Abbas is the only son of Ma'mun, who in 828–829 had appointed him as governor of Al-Jazira (Upper Mesopotamia) and the Mesopotamian military frontier zone (thughur) with the Empire.

Abbas had distinguished himself by his bravery in the expeditions against the imperial forces.

An expedition led by Abbas against the Khurramite rebels of Babak Khorramd in in Azerbaijan in summer 830 had been accompanied by a contingent of Greek captives under the renegade general Manuel the Armenian, who, given Abbas's relative inexperience, may have been the actual commander of the army.

Abbas's force had met with some success against the Khurramites, and began its return.

As it passed near the frontier at Adata, Manuel, having earned the confidence of Abbas and his Arab officers, had persuaded Abbas to cross the nearby passes and raid imperial territory.

Once there, Manuel had taken advantage of a hunt to disarm Abbas and his entourage and defect back to the Empire, along with some of the other captives.

Abbas with his men had been left behind and after rejoining their army, they had retreated back over the mountains into the Caliphate.

In the next year, however, Abbas accompanies his father and uncle in a major expedition into imperial Anatolia.

After the Arab army crosses the Cilician Gates and takes Heraclea Cybistra in early July, it divides in three corps, headed by the Caliph, Mu'tasim and Abbas, and proceeds to raid across Cappadocia.