Charles Ellicott Commentary Genesis 12:8

"And he removed from thence unto the mountain on the east of Beth-el, and pitched his tent, having Beth-el on the west, and Ai on the east: and there he builded an altar unto Jehovah, and called upon the name of Jehovah." — Genesis 12:8 (ASV)

He removed. —Broke up his encampment. No special reason for this needs to be sought; it was the usual condition of the nomad life, and Abram’s wealth in cattle would make frequent changes necessary.

His first long halt was in the hill country between Beth-el and Hai, or rather Ai, as in Joshua 8:1-3. The numerous almond-trees, from which the former town took its early name of Luz, the remains of aqueducts and other works for irrigation, and the strength of the town of Ai in Joshua’s days bear witness to the ancient fertility of the district, though now said to be uninviting. Here, too, Abram made an open profession of his faith and worshipped with his household at an altar dedicated to Jehovah.