Article 1, Section 9, Clause 8
Document 10
Thomas Jefferson to William Temple Franklin
20 Apr. 1790Papers 16:363We are now about making up our minds as to the presents which it would be proper for us to give to diplomatic characters which take leave of us. For this purpose it is important to know what are given by other nations. Not foreseeing that I might ever have any thing to do with the decision of such a question, I did not inform myself of the usage even in the court with which I resided. Perhaps you may have had occasion to learn their practice, and particularly I presume you can inform me of the estimated value and the form of the present they gave Dr. Franklin on his departure. This, and any other information you can give me as to the distinction they make between different grades in their farewell presents will much oblige me.
The Founders' Constitution
Volume 3, Article 1, Section 9, Clause 8, Document 10
http://press-pubs.uchicago.edu/founders/documents/a1_9_8s10.html
The University of Chicago Press
The Papers of Thomas Jefferson. Edited by Julian P. Boyd et al. Princeton: Princeton University Press, 1950--.