They 'swore' (an oath of) allegiance to the United States of America. [=they formally promised that they would be loyal to the United States of America]
He 'swore us to secrecy/silence'. [=he made us promise not to tell anyone his secret]
He was so disgusted by the election results that he 'swore off' politics for good.
(..) annoying'' and then white noise. Will, l got him to quit smoking. For ever? No last one? The last ones are better than sex. Trust me, l've had of them. Done forever, he swore to me. l reached him. l reached him. You're having a big day, there, Susan. Private party. - Dr Cox, about Will. (..)2001 TvShow: Scrubs Title: My Mentor Season: 1 Episode 2