Article 1, Section 8, Clause 12

Document 1
Bill of Rights, sec. 6
1 W. & M., 2d sess., c. 2 , 16 Dec. 1689
That the raising or keeping a standing army within the kingdom in time of peace, unless it be with consent of parliament, is against law.

The Founders' Constitution
Volume 3, Article 1, Section 8, Clause 12, Document 1
http://press-pubs.uchicago.edu/founders/documents/a1_8_12s1.html
The University of Chicago Press