Epitaph or idiomatic expression to someone who has died
Rest in peace (R.I.P.), a phrase from the Latin requiescat in pace (Ecclesiastical Latin: [rekwiˈeskat in ˈpatʃe]), is sometimes used in traditional Christian services and prayers, such as in the Catholic, Lutheran, Anglican, and Methodist denominations, to wish the soul of a decedent eternal rest and peace. It became ubiquitous on headstones in the 19th century, and is widely used today when mentioning someone's death. Description.
https://en.wikipedia.org/wiki/Rest_in_peace