Article 1, Section 8, Clause 15

Document 2

Virginia Declaration of Rights, sec. 13

13. That a well regulated militia, composed of the body of the people, trained to arms, is the proper, natural, and safe defence of a free state; that standing armies, in time of peace, should be avoided, as dangerous to liberty; and that, in all cases, the military should be under strict subordination to, and governed by, the civil power.

The Founders' Constitution
Volume 3, Article 1, Section 8, Clause 15, Document 2
http://press-pubs.uchicago.edu/founders/documents/a1_8_15s2.html
The University of Chicago Press