NOTES for Gen 13:12-18
The entire history set out in the Pentateuch is the history of the covenant, the history of those relations between God and His people whose description forms the Bible's historical thread, tying together its books, though they are so unlike one another. And now, when Abraham and Lot have gone in different directions, God confirms the covenant previously made with Abraham, again repeating that the land he sees around him will belong to his descendants. Is there a connection between these two events?
At first glance, Lot's separation can have nothing to do with God's covenant with Abraham. Lot, it appears, does not look very deeply into anything connected with the covenant: like most of Abraham's fellow tribesmen, he leaves relations with God to the leader's discretion. But God, as can be seen, is not indifferent to which tribes will make up His people. At first glance, why is Lot's clan worse than Abraham's, especially since they are relatives, and fairly close ones at that? Meanwhile, the answer to the question is not hard to find in the text itself: Lot is ready to settle anywhere, as long as he likes the local landscape and climate. His surroundings do not frighten him: he apparently thinks that the sins of the local inhabitants, among whom he will have to live, will not touch him. Abraham acts far more cautiously in this regard and tries to keep away from the Palestinian cities with their corruption (in every sense of the word), although that choice forced him to give up the chance to settle in lands far more favorable in natural and climatic terms than the Samaritan steppe in which he had to live.
Had Lot and Abraham remained together, the latter would have had to take the former's demands into account, and this would inevitably have limited his ability to decide where to live and where to go next. By separating from Lot, Abraham frees his hands and receives the freedom of action necessary for the leader of God's people. And then God confirms His covenant with him.