إِنَّا لِلَّهِ وَإِنَّا إِلَيْهِ رَاجِعُونَ
"Indeed we belong to Allah, and indeed to Him we will return."
Reflection
This is the dua of the bereaved — Inna lillahi wa inna ilayhi raji'un. It reminds us that everyone and everything belongs to Allah. The one you lost was His before they were yours, and they have simply returned to their true Owner. This is not goodbye forever; it is "see you later" in the Garden of Eternity.