James Platania argues that Shabbat is not first instituted at creation but is discovered in the wilderness of Sin - prior to its formal legislation at Sinai - through Moses' innovative interpretation of God's previous words and deeds. Focusing on Exodus 15,22-16,36, he argues that the biblical narrator presents Moses as a prophetic mediator who interprets earlier divine discourses in response to new circumstances, prior to any explicit divine command concerning Shabbat. Shabbat thus emerges within Israel's lived experience of manna, before covenantal lawgiving, as a practice discerned and confirmed within narrative time. The author adopts a narrative approach grounded in literary poetics and legal hermeneutics, reading Exodus sequentially from the perspective of a first-time reader and treating the final form of the text as primary. Particular attention is given to Moses' speeches and their attributional reference to prior divine utterances, as well as to narrative gaps that invite the reader to infer processes of interpretation and legal innovation. The academic contribution of the book lies in bringing narratology and legal hermeneutics into sustained dialogue. By reading scribal strategies of innovation as dramatized within the narrative world, the author reframes Moses as an exegetical prophet whose authority legitimates legal development. Geographically, the study is situated in the wilderness traditions of Exodus, and temporally it addresses the pre-Sinaitic phase of Israel's journey. Theoretically, it offers a model for understanding biblical law as narratively mediated and dynamically unfolding, with implications for the study of Shabbat, legal innovation, prophetic authority, and Pentateuchal composition.