Abu Yusuf al-Qadi

Abu Yusuf Yaqub ibn Ibrahim al-Ansari was the chief judge (Qadi al-Qudat) under Caliph Harun al-Rashid and one of the most important students of Imam Abu Hanifa. He helped systematize and codify Hanafi jurisprudence and played a crucial role in its spread as the official legal school of the Abbasid Caliphate. His Kitab al-Kharaj (Book of Taxation) is an important early work on public finance in Islamic law.