He shall take the cedarwood, the hyssop…and he shall sprinkle upon the house seven times.
Meshech Chochmah: The pasuk does not explicitly identify which part of the house should be sprinkled. Chazal, however, establish that the sprinkling should be aimed specifically at the lintel of the door.
This small detail dovetails nicely with Chazal’s understanding of the lesson of nega’im. They sensed in the Torah’s words “The one to whom the house belongs shall come” the crucial failing of the person whose house was stricken with a nega: extreme possessiveness. Such a person balks at lending any of his possessions to others. When asked, he replies that he does not own the item that his neighbor seeks to borrow. Appropriately, when a nega develops in his house, all his goods are removed from it before it is declared tameh. This means that his property – and all his blatant lies about what he did not own – are put on public display. When the nega subsides and he presumably has internalized the lesson it was meant to teach, the blood and water mixture is sprinkled specifically on his door, proclaiming that from here on, it should remain open to people, rather than shut as before.
Whereas a house-nega indicates possessiveness and miserliness, a skin-nega is the spiritual reaction to evil and frivolous speech. The victim should have protected himself from hearing such speech, says the gemara, by inserting his finger tips into his ears to block the sound. When a person is healed of such a nega, the ritual he goes through points directly at his failing. The sprinkling is done, fittingly enough, to his hand!
Thus, in regard to both of these nega’im, on houses and on human skin, the sprinkling is done to an object that points back at an earlier failing. This finding is attractive – but not, however, entirely accurate. The gemara elsewhere counts off seven causes for skin-nega’im: lashon hora, murder, empty oaths, sexual immorality, haughtiness, theft – and miserliness! Apparently, it is not only the miser’s house that can be affected, bringing home the lesson that his door needs to be opened wider. Sometimes, his very body is affected. Why? What connects a failing in the way he utilizes his property with his body?
The answer might be that improper use of one’s property ramifies upon relationships much deeper than the bond between a person and what he owns. The social structure of the community is impacted. When a person is perceived to be miserly and stingy, he develops a reputation for being anti-social. He is seen as uncaring, as shunning the company of men – and men come to shun him. Socialization requires that people be able to give and take – literally – from each other. The person who lives in his own fortress abstracts himself from the community, whether he recognizes it or not.
When he doesn’t, the Torah lets him know it. He is forced to dwell apart from other people. He can not even solace himself in the company of other unfortunates who have been stricken with nega’im. He is instructed to dwell alone, in solitude.
This might explain an anomaly in the laws of korbanos. While most korbanos standardize the nature of the offering, in certain cases the Torah allows for different offerings depending on the fiscal well-being of the donor. The rich are told to bring animals, while the poorer bring birds or even flour. The law is that if a rich person brings his offering from an economic class beneath his own, he has nonetheless fulfilled his obligation – with the exception of the metzora. While there are other satisfactory explanations for this, one way of looking at it follows from our discussion above. Since the nega can be visited upon him for miserliness, his atonement must address his shortcoming. If he continues his penny-pinching ways even as he walks on to the Temple Mount, he has not internalized the lesson of our parshah, and therefore does not fulfill his obligation.
 Based on Meshech Chochmah, Vayikra 14:51
 Toras Kohanim 5:14
 Yoma 11B
 Vayikra 15:35
 Kesubos 5B
 Arachin 16A