Final answer:
The quote is from the Articles of Confederation, which served as the United States' first constitution, establishing a league of friendship and a weak national Congress that the states often ignored.
Step-by-step explanation:
The quote "Instead of forming a strong national government, the states entered into ... a firm league of friendship with each other..." originates from the Articles of Confederation. This was the first governing document of the United States, created to bind the 13 original states together in a "firm league of friendship" for mutual defense and general welfare, yet allowing for each state to maintain its sovereignty and independence. The Congress established by the Articles had limited powers, lacking an executive branch, national judiciary, or the ability to impose taxes. As a result, the states often ignored Congress's laws, leading to the realization that a stronger national government was needed, paving the way for the drafting of the U.S. Constitution.