The phrase "be needful" is often used to convey the idea of something being necessary or essential. There are a variety of synonyms that can be used to express this concept, depending on the context in which it is being used. Some possible alternatives include "be required," "be vital," "be crucial," "be imperative," "be indispensable," and "be obligatory." Each of these words conveys a sense of urgency or importance, highlighting the fact that something must be done or obtained in order for a situation to be successful or satisfactory. By using these synonyms, writers and speakers can add variety and emphasis to their language, while still conveying the same essential meaning.