'River' in the Bible

He sent messengers therefore unto Balaam the son of Beor to Pethor, which is by the river of the land of the children of his people, to call him, saying, Behold, there is a people come out from Egypt: behold, they cover the face of the earth, and they abide over against me:

And the border shall fetch a compass from Azmon unto the river of Egypt, and the goings out of it shall be at the sea.