Article 6, Clause 2
Document 23
James Madison, Virginia Resolutions
21 Dec. 1798(See Amend. I [speech and press], no. 19 )
The Founders' Constitution
Volume 4, Article 6, Clause 2, Document 23
http://press-pubs.uchicago.edu/founders/documents/a6_2s23.html
The University of Chicago Press