In the same day the LORD made a covenant with Abram, saying, Unto thy seed have I given this land, from the river of Egypt unto the great river, the river Euphrates: The Lord made a covenant - כרת ברית carath berith signifies to cut a covenant, or rather the covenant sacrifice; for as no covenant was made without one, and the creature was cut in two that the contracting parties might pass between the pieces, hence cutting the covenant signified making the covenant. The same form of speech obtained among the Romans; and because, in making their covenants they always slew an animal, either by cutting its throat, or knocking it down with a stone or axe, after which they divided the parts as we have already seen, hence among the percutere faedus, to smite a covenant, and scindere faedus, to cleave a covenant, were terms which signified simply to make or enter into a covenant.
From the river of Egypt - Not the Nile, but the river called Sichor, which was before or on the border of Egypt, near to the isthmus of Suez; see Joshua 13:3; though some think that by this a branch of the Nile is meant. This promise was fully accomplished in the days of David and Solomon. See 2 Samuel 8:3, etc., and 2 Chronicles 9:26.