The Hebrew idiom used in this verse is much sweeter than the English translations.“Left” and “right” are actually “left hand” and “right hand.” Abram isn’t telling Lot to go far away from him. These aren’t opposites. He’s indicating nearness, as they are still one body.
Is the entire land not before you? Please separate from me; if you choose the left, then I will go to the right; or if you choose the right, then I will go to the left.
Genesis 13:9 (NASB)
אם השמאל ואימינה IF THOU WILT TAKE THE LEFT HAND, THAN I WILL GO TO THE RIGHT —Wherever you settle down I will not go far from you and I will stand by you as a shield and as a helper. Ultimately, indeed, he (Lot) was really in need of him, as it is said, (Genesis 14:14) “And Abram heard that his brother was taken captive etc.”
Rashi Genesis 13:9:1