"And there was quarreling (Riv) between the herdsmen of Avram’s livestock and the herdsmen of Lot’s livestock… So Avram said to Lot, “Please let there be no strife (M’ree’va) between me and you…” (Genesis 13:7-8)The Torah first labels the argument between the herdsmen of Avraham and Lot as a “Riv,” but shortly afterwards calls it a “M’ree’va.” Both words mean exactly the same thing: ‘quarreling’ or ‘strife.’ The only difference between the two words is that Riv is in masculine-form, while M’ree’va is in feminine-form.
Why the switch?
The Shelah HaKadosh explains that an argument usually proceeds along a natural pathway. A disagreement usually begins as something that is relatively small, but since it’s rarely dealt with properly at the early stages, it mushrooms and begets more fighting and side-issues that expand beyond the subject of the original disagreement.
In this respect, the Shelah remarks that a Machlokes (dispute) is akin to a woman who becomes pregnant and subsequently gives birth to offspring.
It is for this reason that the quarrel between the herdsmen of Avraham and Lot switches from masculine to feminine form.
In essence, Avraham was telling Lot that they’d be wise to part ways before their dispute would escalate out of control! Shelah HaKadosh also says that the physical structure of the word “Machlokes” in Loshon HaKodesh (Hebrew) hints to the natural way a dispute grows and grows.
The letter Mem has a small opening, but opens much wider in the following letter, Ches. The next two letters are Lamed and Kuf, and they go up and down. So now we see it widening, and also spreading in all directions! The last letter of the word, Taf, has two legs, to show that at this point, it’ll be sturdy and sadly remain… And Shelah comments that the Vav in the middle represents a stick of Machlokes, or a snake.