And there was friction between Avram's herdsmen and Lot's herdsmen...and Avram said to Lot 'Let's not have friction between me and you and my herdsmen and your herdsmen'(Biraishis 13:7-8).
The Netziv explains that Avram told Lot that he was afraid that the herdsmen's fight might spill over to them, as it says in Mishlei 17:14 "The beginning of strife is like letting out water". ie.If you
have a small hole in a water barrel, the more water goes through it, the bigger the hole gets. Quarreling is like a poisonous growth: Nip it in the bud !!