U.S. Constitution, Article I — The Legislative Branch, Section 3, Clause 4
The Vice President of the United States shall be President of the Senate, but shall have no Vote, unless they be equally divided.
Notes
Establishes the Vice President of the United States as the President of the Senate, and limits the Vice President's vote to cases where the Senators are equally divided. Outside a tie, the Vice President presides over the Senate but has no vote on the matters before it.
Use as reference
Lexinter.net | U.S. Const. art. I, § 3, cl. 4 | https://laws.lexinter.net/constitution/us/article-1/section-3/clause-4