When the Canaanites of the land saw the mourning at the threshing floor of Atad, they said, “This is a solemn ceremony of mourning by the Egyptians.” Thus the place across the Jordan is called Abel-mizraim.
Jewish Publication Society of America Version (JPS1917) - Genesis 50:11 >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 Abel-mizraim, which is beyond the Jordan.