Verses with the word atad in the Old Testament (2 verses):

Genesis 50:10
And they came to the threshingfloor of Atad, which is beyond Jordan, and there they mourned with a great and very sore lamentation: and he made a mourning for his father seven days.

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 Abelmizraim, which is beyond Jordan.