Kitab al-Kharaj by Abu Yusuf is a monumental work of early Islamic jurisprudence, focusing on land tax (kharaj) and state revenue. Commissioned by Caliph Harun al-Rashid, it provides comprehensive insights into the economic, administrative, and legal principles governing the Abbasid state. Abu Yusuf, a leading Hanafi scholar and chief judge, meticulously outlines regulations concerning land ownership, taxation systems, public spending, and the ethical responsibilities of rulers. This treatise remains a crucial source for understanding Islamic fiscal policy, demonstrating the sophisticated framework of governance in the classical Islamic world and its enduring relevance to economic history and political thought.