Charles Ellicott Commentary Genesis 20:7

"Now therefore restore the man`s wife. For he is a prophet, and he shall pray for thee, and thou shalt live. And if thou restore her not, know thou that thou shalt surely die, thou, and all that are thine." — Genesis 20:7 (ASV)

He is a prophet. —This is not said as an aggravation of Abimelech’s sin, but as an encouragement to him to restore Sarah. It is therefore rightly joined with the words He shall pray for you. For the word prophet is used here in its old sense of spokesman (Compare Exodus 7:1 with Genesis 4:16), and especially of one who mediates between God and man. There was a true feeling that God in His own nature is beyond the reach of man (Job 9:32–33; Job 16:21; 1 Timothy 6:16); and this in heathen nations led to people populating their heavens with a multitude of minor deities.

In Israel, after the founding of the prophetic schools by Samuel, the prophets became an order, whose office was partly to enliven the services of the Temple with sacred music and song (1 Chronicles 25:1), but chiefly to be God’s spokesmen, both declaring His will to Jew and Gentile (Jeremiah 1:5), and also maintaining religion and holiness by earnest preaching and other similar means.

In this way they were forerunners, and even representatives, of Christ, who is the one true and only Mediator between God and man. Not only Abraham, therefore, but the patriarchs generally are called Christs and prophets (Psalms 105:15), as being speakers for God to man, and for man to God, until the true Christ and prophet came.

Abimelech, moreover, is thus taught that he himself does not have a close relationship with God but requires someone to speak for him; perhaps, too, he would understand from this that he needed more complete instruction, that he ought to try to attain a higher level, and that Abraham would become a prophet to him in its other sense of being a teacher. (For the prophet as an intercessor, see Exodus 8:28-29; Deuteronomy 9:19–20; 1 Samuel 7:5; 1 Samuel 12:19; 1 Samuel 12:23; 1 Kings 13:6; Job 42:8.)