Abu Yusuf (729-798), was born in Kufa. He, who had be lived in the last quarter of the eighth century; is one of the most efficient personalities of Islamic Civilization. Abu Yusuf; within of Hanafi school who is the one of fiqh schools of the science of fiqh it has been created and developed by Islamic civilization; as he during own time was reached to the summit, at the same time, had created affect penetrating the centuries in the case laws. Under Islamic tradition; worships and transactions and at the other subjects, vastly his views apply. In particular, the case law on foundations in practice still continues. In lived period; made effort against for the most complex social, political and economic problems in the book and the Sunnah light, finding a solution, his was thanks to genius. "Kitab al Harac" is his most important work.