The imperative is used to express a request, command or instructions.

Use the formal imperative for people addressed with the polite form "Sie". There is no difference between the singular and plural formal imperative. It is formed by the 3rd person plural present tense. Unlike the informal imperative, a sentence in the formal imperative keeps the personal pronoun, which comes after the verb.

The imperative form "sein" is irregular.

Example:
Sie sind nicht verrückt. Seien Sie nicht verrückt!