In this week's parshah the Torah relates the entire saga of קרח ועדתו, Korach and his followers, who incited a rebellion against Moshe Rabbeinu. They challenged Moshe's leadership and the assertion that only Aharon could perform the duties of a Kohen Gadol. The Torah tells us how they continued challenging Moshe until the tragic end, when Korach and the chief agitators were swallowed into a hole in the ground, and the two-hundred and fifty men who joined him were consumed by a heavenly fire.
Towards the end of this episode, the Torah warns us ולא היה כקרח וכעדתו (יז ה), and it should not be like Korach and his assembly. Never again should such an occurrence take place, where people create and join strife and fighting. With this possuk the Torah is cautioning us to remember that which Korach and his people did, as well as the tragic results thereof so that a lesson should be gleaned from it.
In fact, for this explicit reason, Hashem commanded Elazar the son of Aharon to repurpose the pans used in this episode. When the two-hundred and fifty supporters of Korach were maktir ketoros, as a test to see who has the right to perform the avodah, they were consumed by a fire from above. This was an open display of Heavenly justice. The pans they used, however, were not burned and they acquired a holy status, as they had been used in an attempt at offering ketoros. Elazar therefore was to take these pans and create a plating, a cover, for the mizbeach out of them. Thus, everyone who will see it will remember what happened when the כהונה was challenged, and when people tried to stir up machlokes with the leaders of the generation. Remembering the tragic results will serve as a deterrent for such an occurrence taking place again. Therefore, after the Torah relates that the pans were repurposed, the possuk concludes ולא היה כקרח וכעדתו.
The Gemara (סנהדרין קי.) also learns from this possuk a לאו, a prohibition, against creating, joining, or holding onto a dispute. When the Chofetz Chaim (פתיחה לאוין יג) enumerates all the prohibitions one can transgress when speaking loshon hara, he includes this one too, ולא היה כקרח ועדתו. For often, speaking loshon hara can cause or fan the flames of machlokes, which is a לאו the Gemara references from this possuk.