In Baghdad
Al-Shaybānī moved to Baghdad, where he continued his learning. He was so respected that Caliph Harun al-Rashid appointed him qadi (judge) of his capital city Ar-Raqqah (so, after 796 CE). Al-Shaybānī was relieved of this position in 803. He returned to Baghdad and resumed his educational activities. It was during this period he exerted his widest influence. He taught Muhammad ibn Idris ash-Shafi`i, the most prestigious of his pupils. Even later, when ash-Shafi'ī disagreed with his teacher and wrote the K. al-Radd ʿalā Muḥammad b. al-Ḥasan ("Refutation of Muḥammad b. al-Ḥasan "), he still maintained immense admiration for his teacher.
Al-Rashid re-instated al-Shaybānī in a judicial position. The latter accompanied the caliph to Khorasan, where he served as qadi until his death in 805 at Rey. He died the same day and the same place as the eminent philologist and grammarian al-Kisāʾī. Thus, al-Rashid remarked that he "buried law and grammar side by side."
Read more about this topic: Muhammad Al-Shaybani