Charles Ellicott Commentary Exodus 23:31

"And I will set thy border from the Red Sea even unto the sea of the Philistines, and from the wilderness unto the River: for I will deliver the inhabitants of the land into your hand: and thou shalt drive them out before thee." — Exodus 23:31 (ASV)

Thy bounds. —Those whose highest understanding of prophecy identifies it with advanced human foresight naturally object to Moses having foretold the vast extent of empire which did not take place until the days of David and Solomon.

It is impossible, however, to understand this passage in any other way than as an assignment to Israel of the entire region between the Desert, or “Wilderness of the Wanderings,” and the Euphrates on the one hand, the Mediterranean and the Red Sea on the other. “The River” (han-nahar) has no other meaning in the Pentateuch than “the Euphrates.” And this was exactly the extent to which the dominions of Israel reached under Solomon, as we see from the description in Kings and Chronicles (1 Kings 4:21; 1 Kings 4:24; 2 Chronicles 9:26). It had, according to Moses (Genesis 15:18), been already indicated with sufficient precision in the original promise made to Abraham.