The chapter is in two parts. Firstly, a phenomenological model of unity of knowledge premised on a systemic way of understanding oneness of the divine law for the world-systems is presented. The methodology of such a worldview is proved to be universal for ‘everything’. Yet specificity is taken up by applying this worldview methodology to specific problems and issues. The case of Tawhid, Islamic monotheism, is taken up in the context of this systemic understanding of unity of knowledge in the formation of Islamic market. What is the ethical and moral foundation of the Islamic (so-called Shari’ah) market? Upon the answer to this epistemological question, the nature of knowledge and the learning systems are formulated. The endpoint is to define the concept of Islamic market in the light of the phenomenological model of unity of knowledge according to the Tawhidi methodological worldview.