In Rest Assured Meaning?

phrase. If you say that someone can rest assured that something is the case, you mean that it is definitely the case, so they do not need to worry about it.

Is it correct to say be rest assured?

*Please be rest assured that... is absolutely wrong. 'Rest assured' simply means something like "Don't worry". You say this when you're confident that something will happen. You're making a sort of promise that you will accomplish something.

Where does rest assured come from?

This word comes from the Old French rester, meaning to remain, which takes its roots in the Latin restare, meaning to stand back or be left. This Latin word comes from the prefix re- meaning back, and the root stare, which means to stand. The phrase rest assured became common between the 16th and 17th centuries.