Deuteronomy 34:6-8

6He buried him Or He was buried in Moab, in the valley opposite Beth Peor, but to this day no one knows where his grave is. 7Moses was a hundred and twenty years old when he died, yet his eyes were not weak nor his strength gone.

8The Israelites grieved for Moses in the plains of Moab thirty days, until the time of weeping and mourning was over.