The Lord appeared unto Abram, to encourage and comfort him against his wicked neighbours: see Genesis 13:15, Genesis 15:18 17:8 24:7 Deuteronomy 34:4. There built he an altar, a place for sacrifice, and other parts of Divine worship, erected by him both to keep his family in the true religion, and to separate himself and them from that idolatrous neighbourhood.
Related Commentaries of Genesis 12:7
Genesis 12:7
7 And the LORD appeared unto Abram, and said, Unto thy seed will I give this land: and there builded he an altar unto the LORD, who appeared unto him.