What does "from the river to the sea" mean?

When Abraham answered the call of God and came into the land of Canaan, God promised that his descendants would inherit the land, "from the river of Egypt to the great river, the river Euphrates" (Gen. 15:18). Again, when speaking to Moses about the inheritance of Israel, the Lord said, "I will set your border from the Red Sea to the Sea of the Philistines, and from the wilderness to the Euphrates" (Exodus 23:31). The Euphrates was of such importance in the ways of God that it is called "the river". This river is God's geographical centre of the earth, for Messiah's dominion is spoken of in Psalm 72:8 as "from sea to sea, and from the river to the ends of the earth".

"From sea to sea" speaks of the Mediterranean to the Persian Gulf, and the river is the Euphrates, bordering the northeast. To the ends of the earth would indicate what God said to Abraham, as far as the Nile, the river of Egypt (Gen. 15:18). This defines the extent of Israel's borders in the age to come, the Millennium.

Verses 18-21 speak of an unconditional covenant that the Lord made with Abram that day, telling him that He has given his descendants all the land from the river of Egypt (the Nile) to the river Euphrates, including land at that time possessed by ten different nations. When Israel returned from Egypt they did not possess anything like that whole territory, and never have. But the promise of God stands, and the fulfillment of this awaits the millennium.

This, let us remember, is what Israel never yet has got — the land according to the promise to Abraham... The land of the Sidonians, which was promised to them, they never did possess, nor Mount Lebanon, which was a part of it. Edom, Moab, Ammon, Philistia, are all to belong to them, and never did. Though David's empire reached at one point to the Euphrates, it was only over tributary kings, and that land never was Israel's possession.

In Genesis 15 we have the promise founded upon a covenant made with Abraham, also without condition; it is an absolute gift of the country... If you say that the spiritual promises are without condition, by parity of reasoning the temporal ones are. There is as much certainty in the promise made to Abraham, "To you will I give this land," as in those which have been made in favour of us Gentiles.

The promised possession was theirs by divine sovereignty; their prosperity was conditional on their behaviour; and so it is with the Christian.

But the Messiah will come in power and have dominion over all the earth, as verse 10 declares. The way His widespread kingship is stated here agrees exactly with the inspired statement through David centuries before written in Psalm 72:8... What our prophet tells us is that the days of warfare will be over — chariot and battle bow cut off, and peace imposed upon the nations.

If Zechariah 9:9 foretells Israel's blessing under their King, the following verse gives Him a wider domain: "And He shall speak peace to the nations; and His dominion shall be from sea to sea, and from the river to the ends of the earth." It is no wonder then that the Greeks desire to see Jesus, for the picture of Zechariah 9 could not be complete without the Gentiles.