Deviation is one of the fundamental concepts in modern stylistics, first introduced by the Russian Formalists and later systematically formulated by Geoffrey Leech. Leech defines deviation as the conscious departure from conventional linguistic norms, which leads to the foregrounding of meaning and attracts the audience's attention, and he classified it into eight types: semantic, syntactic, lexical, phonological, stylistic, dialectal, temporal, and graphological. The present study, relying on this model, examines and analyzes the types of deviation in Nahj al-Balagha. The main objective of this study is to identify the types of deviation in the sermons, letters, and aphorisms of Nahj al-Balagha and to explain the role of each in foregrounding meaning. The research method is descriptive-analytical, and the data were extracted by citing examples from the text of Nahj al-Balagha and analyzed within the framework of Leech's theory. The findings demonstrate that semantic and syntactic deviation have the highest frequency in Nahj al-Balagha, and Imam Ali (PBUH), by employing metaphor, simile, paradox, fronting and postponement, ellipsis, and parenthesis, has foregrounded monotheistic, ethical, and doctrinal concepts. In contrast, graphological and temporal deviation have the lowest presence. The conclusion is that deviation in Nahj al-Balagha is not accidental but rather a conscious and purposeful strategy for transferring meaning from the level of information to the level of persuasion and emotional impact.