/tu swɛr æz ə ˈwɪtnəs/ – Phrase
Definition: tuyên thệ với tư cách là nhân chứng.
A more thorough explanation: To swear as a witness means to make a solemn declaration, under oath, that the testimony one is about to give in a legal proceeding is true and accurate to the best of their knowledge and belief. This act is typically done in a court of law or during a deposition, and failing to tell the truth after swearing as a witness can result in charges of perjury.
Example: I solemnly swear to tell the truth, the whole truth, and nothing but the truth, so help me God.