Moses
Genesis 13:6ESV·traditional attribution

so that the land could not support both of them dwelling together; for their possessions were so great that they could not dwell together,

Matthew Henry Presbyterian @wholebiblehenry

We have here an unhappy falling out between Abram and Lot, who had hitherto been inseparable companions (see Gen 13:1, and Gen 12:4), but now parted. I. The occasion of their quarrel was their riches. We read (Gen 13:2) how rich Abram was; now here we are told (Gen 13:5) that Lot, who went with Abram, was rich too; and therefore God blessed him with...

Commenting on Genesis 13:5-9

John Gill Reformed Baptist @doctorgill

And the land was not able to bear them, that they might dwell together,.... That part of the country where Abram and Lot were could not afford them room enough for their several tents; or however could not furnish them with sufficient pasturage for their flocks and herds, they were so numerous; at least could not do it so as to be contiguous to each...

Geneva Bible Notes Reformed @genevanotes

And the land was not able to bear them, that they might dwell together: for their substance was great, so that they could not dwell together. (c) This inconvenience came by their riches, which break friendships and the bounds of nature.