The third century of the hegira represents an extremely important period in terms of the formation process of Islamic sciences and the acquirement of the identity of a systematic school of fiqh madhhabs. In terms of the Zaydiyya madhhab, this century has an identity that affects the next period in terms of both political and scientific studies. Because in this period, the scholars of the madhhab like Kāsim al-Rassî (d. 246/860), Ahmad b. Isā (d. 247/861) and Yahyā b. al-Husayn (d. (...) 298/911), who were in a leading position both in politics and in sciences such as kalām, hadith and fiqh, emerged. Kāsim al-Rassî, who was accepted as the star of the Ahl al-Bayt by Zaydî sources in the first period, was presented as the Plato of Muslims by orientalists in modern studies. The main reason why today's studies on him are mostly about the history of sects and theology, most of Rassî's works are about kalām. However, Kāsim al-Rassî is an important name in the science of fiqh and İslamic legal theory as well as in the science of kalām. According to Abī Tālib Nātik bi’l-Hakk (d. 424/1033), one of the important jurists of the Zaydiyya madhhab, Rassî was a scholar who came to the fore with his ability in fiqh issues; in order to see his ijtihād method, his skill in furû al-fiqh, his mastery in using hadiths and knowing the disagreements of scholars, ‘‘Masā’il al-Dja’far b. Muhammad and Abd Allah b. Hasan” should be consulted. Rassi's epistles named Kitab al-Nāsikh wa’l-Mansūkh, Kitab al-tahāra, Kitab al-salāt al-yevm ve al-Laylā and Kitab al-menāsik are important studies on fiqh that have survived to the present day. In addition, Mueyyed-Billah (d. 411/1021) compiled Kāsim al-Rassî’s and Yahya b. al-Husayn's views on fiqh in his work named al-Tecrîd. Kāsim al-Rassî's views on fiqh are also determinative in later fiqh books such as Tahrîr, al-Cāmi' al-Kāfi, al-Intisār and al-Azhar. In time, the emergence of a jurisprudence sect named Kāsimiyya in Zaydiyya, referring to his name, is also important in terms of revealing his position. Although Rassî's views on fiqh have been referred to a number of studies in our country, no independent study has been found that deals with his views on fiqh. However, considering both of his works on fiqh that have survived to the present day and the early works in which his views are compiled, it is obvious that Kāsim al-Rassî's views on fiqh deserve an independent works. The aim of this study is to reveal Ressî's position within the madhhabs and his perspective on fiqh in general. In this context, in the study, the period in which Ressî lived, his life and works were briefly mentioned, and then the basic views of the fiqh, especially in the field of worship, were discussed in outline. (shrink)