Which part of the Constitution of India declares the ideal of Welfare State?

The Directive Principles of State Policy (Part IV) explicitly mandate the state to promote the welfare of the people by securing a social order characterized by social, economic, and political justice. While the Preamble is tempting because it mentions "Socialist" and "Justice" ideals, it serves as an introductory philosophy, whereas the DPSP provides the substantive constitutional framework for achieving a welfare state. The core concept tested is the distinction between a "Police State," which focuses on law and order, and a "Welfare State," which actively promotes socio-economic equity.