The river of Egypt — Called Sihor, Joshua 13:3, which divided Egypt from Canaan. The sea — The midland sea, called the sea emphatically, whereas the other seas, as they are called, are indeed but lakes.
Related Commentaries of Numbers 34:5
Numbers 34:5
5 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.