The Prophet ﷺ said: whoever says morning and evening, “Raḍītu billāhi rabban, wa bil‑Islāmi dīnan, wa bi‑Muḥammadin ﷺ nabiyyā,” it is a right upon Allah to please him on the Day of Resurrection. (Tirmidhī — ḥasan). These are also the answers to the questions of the grave: your Lord, your religion, your Prophet.
العربية: عن ثوبان رضي الله عنه أنّ رسول الله ﷺ قال: «مَن قال حين يُمسي: رضيتُ بالله ربًّا وبالإسلام دينًا وبمحمدٍ نبيًّا، كان حقًّا على الله أن يُرضيه». (الترمذي وحسّنه).
Say it morning and evening — a few words that secure contentment in this life and the next.