The Prophet (ﷺ) said, When you put death body in grave, say:

بِسْمِ اللَّهِ وَفِي سَبِيلِ اللَّهِ وَعَلَى مِلَّةِ رَسُولِ اللَّهِ

Bismillahi wa fi sabilillahi wa 'ala millati rasoolillah (ﷺ)

With the Name of Allah, in the path of Allah and according to the millat of the Messenger of Allah (ﷺ)

Reference: Sahih. Ibn Majah: 1270