This article examines the concept of “Pretentious Boasting” (i.e., excessive display for fame, a self-aggrandizing and vainglorious veneer—which is considered reprehensible) and explores why such behavior is deemed “futile” or devoid of value—indeed, “repugnant, disgusting, even morally forbidden to sound, whole, or perennial intellect”—within the context of an Islamic worldview grounded in wisdom and knowledge. This worldview is “wise simplicity”, prioritizing “usefulness to the spiritual, intellectual, practical, and physical well-being of individuals and the community”. Relying on divine instruction in the Qur’an and the rational-analytical legacy of the Prophet Muhammad (peace and continual blessings be upon him), his household, and the Shiite Imams, the study highlights their advocacy for: Wise simplicity, Avoidance of pretentious boasting, Nurturing mutual flourishing in a complementary, purposeful system—where the parts work together synergistically to enhance collective well-being. Through analysis of their approach to designing religious law (sharīʿah) and social order grounded in wisdom and knowledge, and their efforts to enact these principles in daily life, this paper identifies derived principles and rulings that shape the aesthetics, structure, and functional design of Islamic art, architecture, and city planning. Applying these principles to the engineering of residential and urban spaces in Iran and other lands influenced by this culture, the article demonstrates how: The ethos of wise simplicity, The imperative to be useful to environments, The principle of complementarity of parts within a purposeful system, The rejection of pretentious boasting, And avoidance of futility of parts are concretely embodied in the geometric design, spatial structure, and ornamental restraint of traditional and contemporary Islamic architecture.