The Preamble to the Constitution

We the people of the United States in Order to form a more perfect Union, establish justice, insure domestic Tranquility, provide for the common defense, promote the general Welfare, and secure the blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution of the United States of America.

This is a Preamble to the Constitution, it is an introduction - not law. When people say that promoting general welfare is written in the Constitution it is not.