On June 8, 1789, James Madison made a statement regarding the introduction of a Bill of Rights, along with the 9th Amendment, which reads:
The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people
Here’s Madison, in his own words:
It has been objected also against a bill of rights, that, by enumerating particular exceptions to the grant of power, it would disparage those rights which were not placed in that enumeration; and it might follow by implication, that those rights which were not singled out, were intended to be assigned into the hands of the General Government, and were consequently insecure. This is one of the most plausible arguments I have ever heard urged against the admission of a bill of rights into this system; but, I conceive, that it may be guarded against. I have attempted it, as gentlemen may see by turning to the last clause of the fourth resolution [the Ninth Amendment].
Annals of Congress. The Debates and Proceedings in the Congress of the United States. “History of Congress.” 42 vols. Washington, D.C.: Gales & Seaton, 1834–56.