When the Canaanites who lived there saw the mourning at the threshing floor of Atad, they said, "The Egyptians are holding a solemn ceremony of mourning." That is why that place near the Jordan is called Abel Mizraim.
NIV
When the inhabitants of the land, the Canaanites, saw the mourning at the floor of Atad, they said, This is a grievous mourning for the Egyptians. Therefore the place was called Abel-mizraim [mourning of Egypt]; it is west of the Jordan.
AMP
And when the inhabitants of the land, the Canaanites, saw the mourning in the floor of Atad, they said, This is a grievous mourning to the Egyptians: wherefore the name of it was called Abelmizraim, which is beyond Jordan.
KJV