A: In Genesis 15:18 God promised Abraham the whole land from the River of Egypt to the Euphrates. Again in Deut 11:24 the Israelites were to inherit all the land from the desert to Lebanon, from the Euphrates to the Western Sea.

2 Chronicles 9:26 describes the Kingdom of Solomon as extending from the Euphrates ("the River") to the Land of the Philistines (Mediterranean coast) down to the border of Egypt.

The most detailed description of the future boundaries of Israel are to be found in Ezekiel 47:15-20

In short, the Land of Israel will eventually include all the land between the Jordan river and the Mediterranean sea, and stretch north of the Jordan's headwaters all the way to the Euphrates and south to "the River of Egypt", evidently a small river in the Sinai which marked the Egyptian border in ancient times.