U.S. Constitution, Article I — The Legislative Branch, Section 9, Clause 8
No Title of Nobility shall be granted by the United States: And no Person holding any Office of Profit or Trust under them, shall, without the Consent of the Congress, accept of any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince, or foreign State.
Notes
Bars the United States from granting any title of nobility, and bars anyone holding a federal office of profit or trust from accepting any present, emolument, office or title of any kind from any king, prince or foreign state without the consent of Congress. Consent from Congress is the only exception.
Use as reference
Lexinter.net | U.S. Const. art. I, § 9, cl. 8 | https://laws.lexinter.net/constitution/us/article-1/section-9/clause-8