This study aims to verify the book of Zakat from the manuscript "AlMudnun bihi 'ala Ghair Ahlihi" by Sheikh Salem bin Saeed Al-Sayeghi, and to identify the methodology and style of the Sheikh in writing this book. To achieve the purpose of the study, the researcher divided the study into four chapters. The introductory chapter is a translation of the author, and the book. Then, in the first chapter, the researcher investigates and study the manuscript, and proved the authenticity of the manuscript's attribution to the author, as she mentioned the reason for authorship, and the author's jurisprudential approach in writing this manuscript. In the second chapter, the researcher studied the issue of Zakat on trade coming from the sea, and the study was divided into three sections: a section related to Muslim merchants coming from the sea, a section related to nonMuslim merchants, and a final section related to Omani merchants coming with their trade from the sea to the port of Sohar and cases that are exempt from ta’shir. The researcher discussed the different opinions and compared them with the opinions of other schools of thought regarding ta’shir (merchandise tax). As for the last chapter, the researcher dedicated it to verifying the book of Zakat according to the standards and rules of verifying Arabic manuscripts that are commonly accepted. The researcher attributed the different statements to their owners. The researcher also proved the Quranic verses and extracted the prophetic hadiths mentioned in the manuscript and explained the meanings of the obscure Arabic words and Omani terminologies.