Administer the oath or affirmation by asking if the person swears or affirms the truthfulness of their statement. The wording may be formulated as a question or a statement depending on your state.
California provides the following wording for an oath or affirmation in the form of questions:
For an oath: “Do you solemnly state that the evidence you shall give in this issue (or matter) shall be the truth, the whole truth, and nothing but the truth, so help you God?”
For an affirmation: “Do you solemnly state, under penalty of perjury, that the evidence that you shall give in this issue (or matter) shall be the truth, the whole truth, and nothing but the truth?” (Code of Civil Procedure 2094[a]).
Florida does not prescribe the form of the oath or affirmation, so you may pose the oath or affirmation as a question or a statement. If posed as a question, the appropriate wording for an oath for a jurat, verification or affidavit may be something like this: “Do you solemnly swear that the statements in this document are true to the best of your knowledge and belief, so help you God?”
Minnesota provides an oath form for affiants that may be used by Notaries who notarize signatures on affidavits: “You do swear that the statements of this affidavit, by you subscribed, are true, so help you God.” (MS 358.07[10])
For an affirmation, MS 358.08 allows the words “swear” and “so help you God” in the abovementioned oath to be replaced respectively with “affirm” and “and this you do under the penalties of perjury.”
Texas provides the following oath or affirmation wording for a person taking public office in the form of a statement: “I _________ (affiant), do solemnly swear (or affirm) that I will faithfully execute the duties of the office of ____________, of the State of Texas, and will to the best of my ability preserve, protect, and defend the Constitution and laws of the United States and of this State (so help me God).”