The actions of Korach and his people created opening for negativity to appear. The people came against Moses and Aaron with complaints and caused greater judgment and plague where 14700 people died in addition to those who perished with Korach.
Immediately after that God gave Moses the laws of the Red Heifer to provided us with a special tool that has the power to remove judgment from all people.
The Red Heifer needed to be flawless, and one that never experienced any kind of work. The reason is that any kind of blemish indicates negativity and a flawed vessel. A red heifer that was used for a work or even if just had a yoke on himself was not qualified to be used for the cleansing process. That would also indicate judgment because work means ‘payment’ and Tikkun process.
The Red Heifer should be an animal without correction process, one that came to this world for the purpose of cleansing judgments and impurities from the world. That means that God sends us a Red Heifer when we need it. In recent years we hear about few discoveries of Red Heifer. B”H it means that the final cleansing of negativity is close.
God promised us (Zechariah 13:2) “וְאֶת-רוּחַ הַטֻּמְאָה, אַעֲבִיר מִן-הָאָרֶץ” “and I will remove the impure spirit from the land.”
The Zohar reveals to us that the process was done by the Elazar, the son of Aaron because Aaron was considered Holy, קדוש and the other priests, ‘pure’. At the same time, any person who dealt with the process of or had direct contact with the ashes and water of the Red Heifer became impure and had to cleanse himself in different ways.
Each time we deal with negativity, even when we try to help others to remove their own, we get in contact with their impurities and these could easily ‘jump’ to us. We wash our hands three times alternating hands, because negativity jumps from one hand to the other until it is satisfied with the ‘light’ given to it.
If negative people came to your home then I suggest purifying the place physically (clean, spray, wash) and then use your favorite incense to cleanse your house from undesired negativity (Evil Eye, Gossip, curses etc.).