Verses 18-21 contain the terms of the promise of the land made to Abram.

On that day does not refer to some time later on the same day, but is an idiomatic way of saying “At that time,” “When that happened,” or as Good News Translation says, “Then and there,” meaning at the very moment the smoke and fire moved between the animal parts.

The LORD made a covenant is literally “cut a covenant,” which may reflect part of the ritual in verses 9-10. For discussion of covenant see 6.18 and 9.9.

Your descendants is “your seed” as in verse 13.

From the river of Egypt: river in Hebrew is nahar, and this term normally refers to the Nile. However, according to Num 34.5; Josh 15.4, 47, the southwestern border of Israel is the brook (Hebrew nahal) in eastern Sinai known today as “Wadi ʿArish.” Speiser says “There is reason to assume, therefore, that the original consonants nhl were misread in this instance as nhr, ‘river.’ ” Good News Translation avoids using either “river” or “brook” by saying “from the border of Egypt….”

To the great river, the river Euphrates: this expression is used in Deut 1.7; Josh 1.4. Good News Translation does not translate the great river; however, most modern translations retain this modifier. These borders do not represent any historical occupation by the Israelites; however, as von Rad says, “The size of the Promised Land corresponds to the extent of Solomon’s kingdom at the period of its greatest extent (1 Kgs 4.21).”

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Genesis. (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .