English is full of expressions that carry both history and nuance. One of those phrases is “rest assured.” You’ve probably seen it in formal emails, motivational speeches, or even in casual conversation. But is it always correct to use it? What does it truly mean, and why do people sometimes write it incorrectly as “be rest assured”?
This guide unpacks the origins, meaning, grammar, and proper usage of the phrase. It also explains common mistakes, provides alternatives, and offers real-life examples so you can use it with confidence.
Introduction: Why “Rest Assured” Matters in English
Language shapes perception. When you write “rest assured,” you’re signaling confidence and reassurance. It’s a phrase often used in professional and personal communication to comfort someone, build trust, or affirm certainty.
However, misuse can weaken your message. Many English learners, and even native speakers, mistakenly add unnecessary words like “be” in front of it. Others confuse it with phrases that sound similar but don’t carry the same nuance.
This article breaks down the expression from every angle – its history, grammar, common mistakes, and practical examples – so you can rest assured that you’ll never misuse it again.
The Origin and Etymology of “Rest Assured”
Understanding a phrase’s roots often makes its meaning clearer.
- The phrase “rest assured” dates back to the 16th century.
- It was frequently used in legal and political contexts to promise certainty or guarantee truth.
- Shakespeare used similar constructions in his plays, cementing his presence in English literature.
Word Breakdown
- Rest: In this context, it means to remain or to stay.
- Assured: Derived from Old French asseurer, meaning to make certain, to secure.
Together, “rest assured” means to remain certain or stay confident.
Historical Example
From a 17th-century English letter:
“Rest assured, sir, that your concerns shall be duly regarded.”
This shows the phrase has long been used to guarantee reliability and trust.
What “Rest Assured” Actually Means
At its core, “rest assured” is an idiomatic expression meaning:
- You can be confident that something is true.
- You don’t need to worry; certainty is guaranteed.
It conveys reassurance, confidence, and reliability.
Contexts of Use
- Business communication: “Rest assured, your payment will be processed securely.”
- Personal reassurance: “You can rest assured that I’ll always support you.”
- Public statements: “Rest assured, the government is taking action to address the issue.”
Common Mistakes with “Rest Assured”
Even though the phrase is widely used, mistakes are common.
Frequent Errors
- Adding “be” unnecessarily: ❌ “Be rest assured, everything is fine.”
- Misplacing the phrase in sentences: ❌ “You can rest assured that we will act.”
- Overusing it in casual speech: The phrase is formal, so using it too much in everyday chatter can sound stiff.
Why It Happens
People often try to make the phrase sound more “complete” by adding “be” or by confusing it with other idioms. But English doesn’t work that way here – the phrase stands strong on its own.
Is “Be Rest Assured” Grammatically Wrong?
Yes, “be rest assured” is incorrect.
Why It’s Wrong
- “Rest assured” already functions as a complete idiomatic phrase.
- Adding “be” introduces redundancy and breaks grammar rules.
Think of it like this:
- Saying “be assured” is like saying “be confident.” It doesn’t make sense.
Correct vs. Incorrect Examples
| Incorrect | Correct |
| Be assured that your order will arrive. | Rest assured that your order will arrive. |
| You can rest assured of success. | You can rest assured of success. |
The Role of Auxiliary Verbs in the Phrase
To understand the mistake better, let’s dive into grammar.
Auxiliary Verbs Refresher
Auxiliary verbs – like be, have, and do – help the main verb express tense, mood, or voice.
In “rest assured,” the phrase itself functions without an auxiliary. “Rest” acts as the main verb, and “assured” is the participle describing the state.
Why Adding “Be” Causes Problems
- “Be” already acts as an auxiliary.
- When you add “be” before “rest assured,” you’re doubling the structure unnecessarily.
Thus, “rest assured” is complete, while “be rest assured” is an ungrammatical invention.
How to Use “Rest Assured” Correctly in Writing and Speech
Here’s how to ensure your usage is precise.
Professional Contexts
- Emails: “Rest assured, we value your privacy and data security.”
- Customer support: “You may rest assured that your request is being processed.”
Personal Contexts
- Conversations: “You can rest assured, I’ll take care of everything.”
- Supportive notes: “Rest assured, you’re not alone in this journey.”
Dos and Don’ts
- ✅ Use it to reassure or guarantee certainty.
- ✅ Place it at the beginning or middle of a sentence naturally.
- ❌ Don’t add extra auxiliaries like “be.”
- ❌ Don’t overuse it where simpler words would do.
Synonyms and Alternatives to “Rest Assured”
Sometimes, variety makes your writing stronger. Here are alternatives:
| Expression | Meaning | Tone/Context |
| Have no doubt | Complete certainty | Neutral/formal |
| Count on it | Dependability | Informal |
| You can be sure | Reassurance | Neutral |
| Be certain | Strong confidence | Formal |
| Trust me | Personal reassurance | Casual |
| Rely on this | Dependability | Semi-formal |
Usage Tips
- In formal writing, use: have no doubt, be certain.
- In casual conversation, use: count on it, trust me.
Practical Examples of “Rest Assured”
Here’s how the phrase works across contexts:
- Customer service: “Rest assured, your complaint will be handled promptly.”
- Leadership communication: “Rest assured, this company will continue to innovate.”
- Personal note: “Rest assured, you’ve got my full support.”
Case Study: Business Email Example
Scenario: A customer is worried about late delivery. Poor Response:
“We are working on your order. Please wait.”
Strong Response:
“Rest assured, your order is on its way and will reach you by Friday.”
The second version builds confidence and reassures the customer.
How to Avoid Confusion: Quick Language Tips
To use “rest assured” like a pro, keep these pointers in mind:
- Remember, it’s a set phrase. Don’t add extra words.
- Use it sparingly. It’s formal, so don’t drop it in casual chats too often.
- Watch similar phrases. Don’t confuse it with “be assured” or “take rest.”
- Think audience first. Use it in business, formal, or supportive contexts.
Final Thoughts
The phrase “rest assured” is more than just a common expression – it’s a linguistic tool that conveys confidence, certainty, and reassurance. When used correctly, it builds trust, strengthens communication, and adds polish to your writing or speech. Misuses like “be assured” not only distract the reader but also undermine the professionalism of your message.
Understanding the origin and grammatical structure of the phrase helps you see why it works without additional auxiliaries. It stands on its own as a complete expression, carrying centuries of usage in literature, law, and everyday communication.
Whether you’re writing a business email, addressing an audience, or comforting a friend, knowing how to apply “rest assured” makes your message stronger and clearer. Its formal tone makes it ideal for professional contexts, while its reassuring quality ensures it remains personal and meaningful.
FAQs
Is it correct to say “rest assured”?
Yes, “rest assured” is correct. It’s an idiomatic phrase meaning “you can be confident” or “you don’t need to worry.” It’s widely accepted in both spoken and written English, particularly in formal or professional communication where reassurance and certainty are needed.
Can I say “be rest assured”?
No, “be rest assured” is grammatically incorrect. The phrase “rest assured” already stands as a complete expression. Adding “be” creates redundancy and breaks standard grammar. The correct form is simply “rest assured” or “you can rest assured.” Always avoid the incorrect variation.
Is “rest assured” formal or informal?
“Rest assured” leans toward formal English. You’ll find it in professional emails, public statements, and official documents. However, it’s also flexible enough for personal use when offering strong reassurance to someone. It’s best avoided in casual small talk, where simpler phrases might work better.
What are synonyms for “rest assured”?
Common synonyms include “have no doubt,” “count on it,” “be certain,” and “trust me.” Each has its own tone. “Have no doubt” fits formal settings, while “trust me” works in casual speech. Choosing the right alternative depends on your audience and the level of formality.
How do I use “rest assured” in a sentence?
You can use it to reassure someone in writing or speech. For example: “Rest assured, your application is under careful review.” Or, “You can rest assured that the issue will be resolved.” Place it naturally at the beginning or middle of a sentence for emphasis.
