Chapter 11 of Tractate Zevachim, Mishnah 3. The Mishnah continues to describe when the blood of a Chatas that splashed onto a garment requires washing.
"Asher yizeh aleha techabes" - Precise Wording:
The verse states: "Asher yizeh aleha techabes" - if the blood splashed onto the garment, the garment requires washing. The word "yizeh" is related to sprinkling, the same term used for the sprinkling of blood on the altar, as well as the sprinkling of Mei Chatas (purifying waters of the red heifer) on one who comes to be purified. This is a puzzling choice of words, as it could have used a term denoting falling - "yipol" - like in other places in the Torah, and there were other options as well. From the fact that the Torah specifically used the language of sprinkling on the altar, the Sages derived that this only refers to blood that was fitting and required to be sprinkled on the altar but was not sprinkled. This derivation is added to the derivation we learned in the previous Mishnah.
Blood That Does Not Require Washing:
"Nitaz min hatzavar al habeged" - if the blood splashed directly from the neck of the Chatas onto the garment, without first being received in a service vessel, this blood is not fit to be placed on the altar and therefore does not require washing. The novelty here is that one might have thought that since until a moment ago the blood was fit to be placed on the altar - since it could have been caught in a vessel - it never had a moment of invalidation. But this is not the case, and therefore it does not require washing.
"Min hakeren umin hayesod" - the blood of the Chatas is placed on the four corners of the altar. If the blood reached the garments of the kohen after it had already been placed on the corner, it has already fulfilled its mission and is no longer valid for further use, and therefore it does not require washing. "Min hayesod" refers even to the stage before the blood reached the base: the primary obligation is to place the Chatas blood on the corners of the altar, and the remainder is poured onto the base. Even if, at the time when there is still an obligation to pour the blood on the base, the blood first reached the garment - since this is not blood required to effect atonement through sprinkling, it does not require washing. And all the more so once it was poured onto the base, at which point its task was completely finished.
"Nishpechah laritzpah va'asafah" - if the blood spilled from the neck of the animal onto the floor, and he gathered it and returned it to the vessel, it certainly does not require washing, since this blood has already been invalidated.
From here the Mishnah arrives at a rule summarizing the entire subject: "Ein taon kibus ela hadam shenitkabel bikli" - blood that went directly from the neck to the sanctified vessel and was fit for sprinkling on the altar.
Which Items Require Washing:
Until now we have dealt with which blood requires washing; from here on we will deal with the question of which items require washing when blood falls on them. The verse speaks of a "garment," and in the language of the Sages a "garment" is almost a code word for an item that is susceptible to tumah. The only question is whether an item that is actively susceptible to tumah is required, or if an item that is potentially susceptible to tumah is sufficient.
The difference relates, for example, to the hide of an animal: if a person decided to leave it as it is and use it as a mat on the floor or for a covering, and he does not plan to perform any further work on it - the hide is susceptible to tumah right now. However, if the owner plans to process that very same hide and make it into a pair of shoes, in its current state it is not susceptible to tumah: although it is potentially susceptible to tumah, a vessel is not susceptible to tumah unless it does not require any further significant work for that function.
Generally speaking, the four categories of items susceptible to tumah are: people, vessels, food, and drink. The hide is not a person, nor is it food or drink, but rather only a vessel, and therefore it must fulfill the requirements of a vessel - that no further work will be performed on it.
The question of the Mishnah is, then, what is the law regarding a hide that the owner - the kohen - has not yet made up his mind about what he will do with it: did he leave it as it is, without the need for further work, and then it is susceptible to tumah right now, or is it merely potentially susceptible to tumah, should he later make up his mind to use it as it is. This is the subject of a dispute among the Tannaim.
The Dispute Between Rabbi Yehudah and Rabbi Eliezer:
Rabbi Yehudah: "Nitaz al ha'or ad shelo hufshat - eino ta'un kibbus" - if the blood splashed onto the hide before it was flayed, it does not require laundering. If blood splashed from the vessel onto the hide of the animal while the hide was still on the animal and had not yet been flayed from it, this is not a vessel - whether it is a live animal, which is not susceptible to tumah, or a carcass afterward - and therefore it does not require laundering, even if it is later made into a vessel. However, "mishehufshat - ta'un kibbus" - once it has been flayed, it requires laundering. Once the hide has been flayed and we have an animal hide before us, if chatas blood gets on it, it must be laundered - not just rinsed or scraped, but actual laundering using those specific laundering agents. Rabbi Yehudah holds that it is enough for the hide to be fit to contract tumah, meaning it is potentially susceptible to tumah, even if it does not actually contract tumah because the owner has not yet made up his mind about its use. Since it is in his power to make up his mind, as it is, it is in a state where it can contract tumah, and therefore it is included in the Torah's obligation like a garment.
Rabbi Eliezer: "Af mishehufshat eino ta'un kibbus" - even once it has been flayed, it does not require laundering. Even after the hide has been flayed, it does not require laundering when chatas blood from a service vessel falls on it. This is because, although it is potentially fit to contract tumah, as long as the person has not made up his mind to leave it as it is - and in the case before us he has not made up his mind - it is not susceptible to tumah right now.
The halachah follows Rabbi Yehudah, that it is sufficient for the hide to be fit to contract tumah. The continuation of the Mishnah also adopts his view, and since it is stated anonymously, we find that the Mishnah itself leans in this direction.
"Eino ta'un kibbus ela mekom hadam" - it requires laundering only in the place of the blood:
The place where the blood splashed requires laundering, but this is merely a localized cleaning - not the entire garment, but only that specific spot. This is derived from the repetitive wording of the verse, which does not settle for the basic obligation to launder. It says, "And that which is sprinkled of its blood on a garment" - if blood splashes on the garment, "that upon which it was sprinkled you shall launder" - the place where the blood fell requires laundering, and not the other places on the garment.
"Vedavar shehu ra'ui lekabel tumah vera'ui lekibbus" - and something that is fit to contract tumah and fit for laundering:
"Ra'ui lekabel tumah" - fit to contract tumah. This means something that has the potential to become tamei. The term "fit" adopts the view of Rabbi Yehudah, and therefore this includes even an animal hide whose future use has not yet been decided.
"Vera'ui lekibbus" - and fit for laundering. It must be the type of item for which laundering is relevant. Laundering means removing something unwanted from the fabric or from the fibers of the material, and this is not just scraping the surface. Therefore, there is no laundering for a piece of glass or metal, since the blood does not penetrate them but remains on their surface and requires scraping and peeling off. We find that the obligation of laundering applies only to absorbent things, such as a garment made of cloth or hide.
The Rema rules that the halachah is as stated. If blood from a valid chatas, which requires laundering, falls on a metal vessel or the like, it will need to be scraped off - since the foundation of the words of the Mishnah and the Chumash is that the chatas blood must be removed. It is just that technical laundering, using those specific agents, is not required when the blood splashes on something into which it is not absorbed.
In summary: In this Mishnah, we learned that the only blood that requires laundering is blood that was received in a vessel and was fit for sprinkling on the Altar. Therefore, blood that splashed from the neck, or that had already been placed on the horn, or that was designated for the base, or that spilled onto the floor and was gathered up - does not require laundering. Furthermore, we discussed the question of the material that requires laundering. "Garment" in the verse refers to something that is susceptible to tumah, and in the dispute between Rabbi Yehudah and Rabbi Eliezer regarding a flayed hide, the halachah was decided like Rabbi Yehudah, that it is sufficient if it is fit to contract tumah. We also learned that laundering is required only in the place of the blood, and only for something absorbent, whereas for a vessel that is not absorbent, scraping is sufficient.