This thesis intends to study the Kit?b al-Iqtib?s f? l-ijtih?d wa l-qiy?s by Shaykh N??ir b. J?cid al-Khar??? (d.1262 AH) generally, and to study and edit the two chapters on ijtihad and taql?d and tac?dul and tarj?? in particular. The study is composed of an introduction, two sections and a conclusion. The first part consists of two chapters, the first of which engages with an introduction of Shaykh N??ir Ibn Ab? Nabh?n and the most important political, societal and economic events of his time. The second chapter engages with the book, its attribution to the author, and introduces to the copy of the edited manuscript. It also discusses the methodology of Shaykh N??ir in his encyclopedia: ?N?r al-Yaq?n wa l-?aqq al-mub?n? which consists of six parts. The researcher concentrated on the sixth part of this encyclopedia and came to the conclusion that it consists of five treatises, containing five books which the Shaykh chose to be the foundation of his book. The fifth treatise, which is partly the subject or our edition, is a comment of Shaykh N??ir on the book of the Zaidi scholar Ibn ??bis, who in turn explained the book ?Al-K?fil bi-nayl l-sawl? of Ibn Bahr?n. The Shaykh?s methodology in these two chapters is characterised by many comments, particularly in the chapter of ijtih?d. The second part of the study consists of the scientific edition of the chapters on ijtihad and taql?d and tac?dul and tarj??, under comparison of the different manuscripts, a correction of the text, identification of the origins of dicta, extraction of Qur?anic verses and Prophetic hadith and explanation of unclear passages in the text. Among the most important results mentioned in the conclusion is that Shaykh N??ir allows the fragmentation of ijtih?d, to the meaning that the mujtahid may exert ijtih?d in some cases to the exclusion of others. He also overweighs that the Prophet (pbuh) exerted ijtih?d as an act of worship. Among the most important recommendations of this study is the necessity to edit and publish the legacy of Shaykh N??ir for the benefit of researchers and readers