Zevachim Chapter 9, Mishnah 4. In this mishnah, we will address the inverse of the rule we learned previously: that which is not taken down from the altar - and that which is not taken up to it a second time.
"Keshem she'im alu lo yeirdu, kach im yardu lo yaalu" - just as if they went up they do not go down, so too if they went down they do not go up:
As we learned in Mishnah 2, there are certain invalidations - technical invalidations, if you will - where once the parts or fats were mistakenly brought to the altar, they must remain there. The mishnah adds: if a second mistake was made, and those items were not left up there but were taken down from the altar, they should not be brought up again. That is to say, something that was brought up invalidly and its law is to remain in its place - shall remain there; but if it was taken down, it does not become permitted thereby, and its law is like that which does not belong on the altar. Therefore, it should not be brought up a second time, but rather left below.
In the Gemara, Ulla explains that all this is specifically when the fire has not yet begun to affect it. We have two situations before us:
Lo mashlah bahen ha'ur - the fire has not taken hold of them: If it was brought up unlawfully and had not yet begun to burn, and then was taken down - it is not brought up again.
Mashlah bahen ha'ur - the fire has taken hold of them: If the fire had already begun to catch and consume what was placed on the altar, the item becomes "the bread of the altar" - the food of the altar, belonging to the altar after the fact, and therefore it must be returned and brought back up.
"Vechulan she'alu chayim lerosh hamizbe'ach - yeirdu" - and all of them that went up alive to the top of the altar - shall go down:
Here the words of Rabbi Akiva continue, who said in the previous mishnah "intent regarding blemished animals". Rabbi Akiva held that animals with a minor blemish - such as an animal with a cataract in its eye - if they went up, they do not go down. Nevertheless, when the animal went up alive to the top of the altar on its own feet, even Rabbi Akiva concedes that they shall go down: it has no business being there, as it was not brought up as a sacrifice but went up on its own, and therefore it is taken down from there.
"Olah she'altah chayah lerosh hamizbe'ach - teired" - an olah that went up alive to the top of the altar - shall go down:
What is the law regarding a regular kosher animal that was dedicated for an olah offering - a cow, goat, or sheep - that went up alive on the ramp of the altar? The law is that it shall go down. We take it down and treat it like a regular olah: we slaughter it in the north, flay it and cut it into pieces, and bring the pieces up in their usual manner.
"Shechatah berosh hamizbe'ach - yafshit viyinate'ach bimkomah" - if he slaughtered it on top of the altar - he flays it and cuts it into pieces in its place:
Here we have a sort of comedy of errors, two mistakes one after another: first, the animal was allowed to go up on the altar - negligent behavior, but that is what happened. Second, even though the law of the mishnah is to take it down, the kohanim slaughtered it up there, on top of the altar.
As you may recall from the sixth chapter, even though most holy offerings like an olah require slaughter in the north - meaning in the northern part of the courtyard, north of the altar - we learned separately that if it was slaughtered on top of the altar itself, its slaughter is valid. Here too, the slaughter performed on top of the altar is valid.
The question is whether the animal is taken back down to the place of slaughter to be flayed and cut into pieces there. The answer is: "Yafshit v'yanate'ach bimkomah" - he should flay and cut it in its place. Since it is already up above, it is not taken down, and the flaying and cutting are done on top of the altar itself. Even though one might have thought it is disrespectful to flay and cut up an animal on the altar, there is nothing preventing it.
All this is aside from two things that certainly do come down from the altar:
The hide: The hide of the flayed animal comes down, is not burned, and is given to the kohanim.
The intestines: With sacrifices in general, the intestines contain waste from the food the animal ate, and they must be cleaned before being placed on the altar. With this olah offering as well, the intestines must be taken down from the altar and washed in the place of washing - a sort of tube is placed at one side and their inside is rinsed out, so that the waste is not brought up onto the altar - and afterward the kohen brings them back up onto the altar.
In summary: In this Mishnah we learned the inverse rule - "Keshem she'im alu lo yeredu, kach im yaredu lo ya'alu" - just as if they went up they do not come down, so too if they came down they do not go up, and that according to Ulla, this depends on whether the fire has taken hold of them and they have become "lachmo shel mizbe'ach" - the food of the altar. We also learned that an animal that went up alive to the top of the altar - even Rabbi Akiva concedes that it should come down; and if it was slaughtered there, its slaughter is valid and it is flayed and cut into pieces in its place, except for the hide which is given to the kohanim and the intestines which require washing before they are brought up.