Sforno on Genesis 12:9/ספורנו על בראשית י״ב:ט׳

1הלוך ונסוע הנגבה, when he journeyed, as is the custom of shepherds, he did not move to the east and to the west alternately, but kept moving in a southerly direction. He did this in order not to deviate from moving between one of the two towns he had been between when he first stopped between Bet El and Ai. Members of those cities had begun to trail him planning to join him.