Perhaps Abram is clinging to God’s perpetual promise: “be fruitful and multiply.” We know from the previous chapter that Sarai is barren, so Abram has no children. No heir of his own, so maybe Lot is the natural successor. Abram might be doing everything to keep his heir safe, thinking that God intends to use Lot to carry out the blessing.
So Abram went up from Egypt to the Negev, he and his wife and all that belonged to him, and Lot with him.
Genesis 13:1 (NASB)
After Abram and Lot separate, God reveals that He’s going to make the barren land bountiful, and we’re given a clue. This appears as a foreshadowing about how God will accomplish His blessings through a barren woman. Abram will have an heir of his own.
May God always surprise us with the way He accomplishes His blessings.