We are beginning the eleventh chapter of Tractate Zevachim, in Mishnah 1. Most of the chapter revolves around the halachos derived from the verses dealing with the sin offering. Let us first read the verses themselves, and point out right now the practical points that we will discuss in the upcoming mishnayos.
The three verses that form the basis of the chapter (Vayikra 6):
"Daber el Aharon v'el banav leimor, zos toras hachatas. Bamakom asher tishacheis ha'olah tishacheis hachatas lifnei Hashem, kodesh kodashim hi" (Verse 18) - From the wording "zos toras hachatas" (this is the law of the sin offering), we expound that there is a unified law applying to all sin offerings. The place of its slaughter is the place where the burnt offering is slaughtered, in the north of the Azarah, because the sin offering is also most holy, and its slaughter is "lifnei Hashem" (before the Lord) - in the Azarah, the courtyard of the Holy Temple. We must pay close attention to the word "tishacheis" (shall be slaughtered) - actual slaughter, as opposed to melikah, as we will see later.
"Hakohen hamchatei osah yochelennah, bamakom kadosh tei'achel bachatzar Ohel Mo'ed" (Verse 19) - The kohen who performs the service of the sin offering is the one who eats it, and eating the sin offering is restricted to kohanim and only in a holy place, because of its status as most holy. "The courtyard of the Ohel Mo'ed" was stated regarding the time of the Mishkan, and in the Holy Temple, the courtyard is the Azarah. It is worth noting that the verse deals with a sin offering that is eaten.
"Kol asher yiga bivsarah yikdash, va'asher yizzeh midamah al habeged asher yizzeh aleha techabes bamakom kadosh" (Verse 20) - "Kol asher yiga bivsarah yikdash" means simply that anything that touches its flesh becomes holy, and this refers to the transfer of taste (similar to the law of absorbed flavors in the laws of kashrus): if the taste of the sin offering transferred to another food, that food must be treated with the same stringencies. We will discuss this matter later in the chapter. Later in the verse: "va'asher yizzeh midamah" - the letter mem is emphasized with a dagesh - if a bit of its blood is splashed "al habeged" (on the garment), specifically on something called a garment, then that garment requires washing "bamakom kadosh" (in a holy place), meaning in the Azarah. In practice: if the blood of a sin offering splashes on the garment of a kohen, the bloodstain requires washing in the Azarah itself.
The text of the Mishnah:
The Mishnah states that the blood of a sin offering that splashed onto a garment "ta'un kibbus" - requires washing. This washing is not merely rinsing in water, but rather a special and precise technique: it must be washed with the seven listed substances, seven specific cleaning agents, and in a fixed order, just as is stated in the halachos of removing a bloodstain.
Inner sin offering and outer sin offering:
The verse in its context speaks of sin offerings that are eaten, as it states that the kohen eats it and that it is eaten in a holy place. However, sin offerings come in two types: the outer sin offering, as well as the inner sin offering - those five sin offerings, the bulls and goats that are burned - which are not eaten at all but are burned in the fire. Nevertheless, the laws of washing apply equally, whether the blood came from an inner sin offering or an outer sin offering.
And so the Mishnah says: Even though the verse in its context speaks of a sin offering that can be eaten, nevertheless, whether it is a sin offering that is eaten, meaning the sin offering of an individual, or a communal sin offering brought on festivals, Shabbos, and Rosh Chodesh - both require washing. And this is because it says "toras chatas" - the law of the sin offering, in the singular: one law for all sin offerings, and one rule applies to them equally. Whether they are inner sin offerings or outer sin offerings, the halachos apply equally, and the blood requires washing in the scenarios that we will describe in the upcoming mishnayos. The main point is that the blood requires washing even for sin offerings that are not fit to be eaten, even though the context dealt with eating.
The bird sin offering:
An additional point: There is another type of sin offering, and that is the bird sin offering, and this law does not apply to it. If the blood of the bird splashes onto the garment of the kohen, the garment does not require washing in the Azarah. The reason for this is that the verse uses the phrase "bamakom asher tishacheis ha'olah tishacheis hachatas" (in the place where the burnt offering is slaughtered, the sin offering shall be slaughtered), and it is speaking of sin offerings that are slaughtered with a knife. The bird sin offering is not slaughtered, but rather melikah is performed on it with a fingernail. Therefore, this law does not apply to it, and the blood of a bird sin offering does not require washing inside the Azarah.
In summary: In this mishnah we learned the source for the law of washing the blood of a sin offering from the verses in Parashas Tzav: the place of slaughter is in the north, the eating of the sin offering is in the Azarah because it is most holy, and the washing of a garment upon which blood splashed is in a holy place, with the seven substances and in their proper order. We also learned that from the wording "toras chatas" it is expounded that there is one law for all sin offerings, whether they are eaten or burned, whether they are of an individual or of the community. In contrast, the bird sin offering, which is not slaughtered but undergoes melikah, its blood does not require washing.