swear

To make a solemn declaration, invoking a deity or a sacred person or thing, in confirmation of and witness to the honesty or truth of such a declaration.

To make a solemn promise; vow.

To use obscene or blasphemous language; curse.

To commit oneself by oath to giving evidence or testimony that is truthful.

To declare or affirm solemnly by invoking a deity or a sacred person or thing.

To say or affirm earnestly and with great conviction.

To promise or pledge with a solemn oath; vow: synonym: promise.

To utter or bind oneself to (an oath).

To administer a legal oath to.