Article 1, Section 9, Clause 4
James McHenry, Maryland House of Delegates29 Nov. 1787Farrand 3:149
Convention have also provided against any direct or Capitation Tax but according to an equal proportion among the respective States: This was thought a necessary precaution though it was the idea of every one that government would seldom have recourse to direct Taxation, and that the objects of Commerce would be more than Sufficient to answer the common exigencies of State and should further supplies be necessary, the power of Congress would not be exercised while the respective States would raise those supplies in any other manner more suitable to their own inclinations.
The Founders' Constitution
Volume 3, Article 1, Section 9, Clause 4, Document 5
The University of Chicago Press
Farrand, Max, ed. The Records of the Federal Convention of 1787. Rev. ed. 4 vols. New Haven and London: Yale University Press, 1937.
Easy to print version.