ことはない

ことはない is used to reassure or deny a possibility, often to say that there is no need to do something or that something will not happen. It adds a nuance of strong negation or reassurance, beyond a simple negative dictionary form. It can convey that a course of action is unnecessary, or that a situation is unlikely or impossible, depending on context. Typical contexts include giving advice, ensuring someone not to worry, or dismissing a potential action as unnecessary.