In Jewish tradition, when someone says בלי נדר, they are expressing an intention or plan to do something but explicitly stating that it is not a formal vow or binding promise. This is done to avoid the serious consequences of breaking a vow (נדר) according to Halacha (Jewish law), where making and not fulfilling a vow is considered a serious offense. By saying בלי נדר, a person is indicating their good intentions but acknowledging that circumstances may prevent them from fulfilling the commitment.