4 U.S. Code § 101
4 U.S. Code § 101 is about Oath by members of legislatures and officers. It is under Chapter 4 (The States) of Title 4 (Flag And Seal, Seat Of Government, And The States) of the Code.
Every member of a State legislature, and every executive and judicial officer of a State, shall, before he proceeds to execute the duties of his office, take an oath in the following form, to wit: “I, A B, do solemnly swear that I will support the Constitution of the United States.”