Pronunciation: [ɹˈɛstɪd əʃjˈʊ͡əd] (IPA) 
The phrase "rested assured" is often misspelled as "rest assured" due to its frequent use in informal conversations. However, the correct spelling includes the əd sound at the end of "rested" to indicate past tense. In IPA phonetic transcription, the word can be written as /ˈrɛstɪd əˈʃʊrd/ to indicate the stress on the second syllable and the final schwa sound. So, the correct pronunciation is "REStid uh-SHOORD".
The phrase "rest assured" is an idiomatic expression used to convey a sense of assurance or certainty regarding a particular matter or situation. It is often employed to assure someone that they can feel confident or secure in a specific outcome or belief. When someone is told to "rest assured," they are being provided with reassurance and told to be at ease because a particular matter has been taken care of or is guaranteed to happen.
The phrase is derived from the concept of restfulness or relaxation, implying that the individual can park their worries or concerns and find tranquility in knowing that a specific issue is being handled or will come to pass. "Rest assured" serves as a verbal confirmation that whatever was causing uneasiness, doubt, or anxiety has been resolved or will unfold as anticipated.
It is often utilized in interpersonal communications to alleviate anxiety, uncertainty, or doubt that someone may be experiencing. By using this expression, the speaker aims to provide a sense of comfort and peace of mind to the listener. "Rest assured" can also be seen as a form of encouragement or support, assuring someone that they need not worry or give undue attention to a certain matter, as it is taken care of.
In summary, "rest assured" is a comforting phrase that assures someone to be confident in the security, certainty, or resolution of a specific issue or situation, encouraging relaxation and trust in the outcome.
The phrase "rest assured" is derived from Old French and has been in use since the 16th century. However, the exact etymology of the phrase is not well-documented.
The word "rest" derives from the Old French word "rester", which means "to remain". "Assured" comes from the Latin word "assūrāre", meaning "to secure" or "to make sure". Over time, these words were combined in English to form the phrase "rest assured".
The expression "rest assured" is used to convey confidence and reassurance. It implies that someone can be calm and confident because they can rely on a particular outcome or because a matter is certain.
It is worth noting that "rest assured" is often used as a standalone phrase without a specific etymology directly associated with it.
