This study examines the phenomenon of stylistic deviation (déviation stylistique) in the celebrated Dāliyya poem of the Moroccan scholar and Sufi mystic Abū ʿAlī al-Yūsī (d. 1102 AH/1691 CE). Drawing on Jean Cohen’s theory of poetic language, it explores how al-Yūsī departs from conventional linguistic norms to generate multiple layers of aesthetic, semantic, and spiritual meaning. The study adopts an analytical approach encompassing the phonological, morphological, syntactic, semantic, and pragmatic levels of the text. It demonstrates that stylistic deviation in al-Yūsī’s poetry is not merely a formal rhetorical device but also a cognitive and mystical act that embodies the Sufi vision of transcendence, unity, and spiritual transformation. The findings reveal that al-Yūsī’s Dāliyya represents a distinctive model of Moroccan Sufi poetry, in which language transcends its representational function to become a medium of revelation, illumination, and spiritual insight. Consequently, stylistic deviation emerges as a dual process of linguistic innovation and spiritual liberation, reflecting the profound interconnection between poetic expression and mystical experience.