Let us move on to chapter 4, mishnah 2. This mishnah is the first place where we deal explicitly with the situation of "the owners have received atonement," and its main novelty concerns the law of money that was set aside for a sin offering.
The text of the mishnah:
"HaMafrish chatato v'avdah" - Reuven consecrated a lamb and said, "This is my sin offering," and afterward the animal was lost.
"V'hikriv acheres tachtehah" - he brought another animal and received atonement through it.
"V'achar kach nimtzeis harishonah" - the first animal was found after the atonement, and its law is that it must die: it is left until it dies, and there is no question here of a first year or anything of the sort.
This is a classic case of "the owners have received atonement," and there is no dispute about it: both according to the Sages and according to Rabbi, when the animal is found at this late stage, after the owners have already received atonement, it is certainly left to die. According to the Sages, had the first animal been found before the second was offered, it would not have been left to die.
One who sets aside money for a sin offering:
The central novelty is found in the second part of the mishnah, which establishes that money set aside for a sin offering has the same law as the sin offering itself: "HaMafrish ma'os l'chatas v'avdu" - a person set aside a purse of money and said that this is the money with which his sin offering will be purchased, and the purse was lost. "V'hikriv chatas tachtehen" - he brought another animal as his offering and received atonement through it. "V'achar kach nimtze'u hama'os" - the money was found after he had already received atonement.
Here too the Sages and Rabbi agree that at this point it is already too late to receive atonement. Money designated for a sin offering is treated as though an animal had already been purchased with it and consecrated as a sin offering. But here there is no animal to be left until it dies, and therefore the mishnah rules: "Yelchu l'Yam haMelach" - the money must be cast into the Dead Sea, so that no one will be able to use it, and it is forbidden to derive benefit from it by rabbinic law. Casting it into the Dead Sea is the monetary equivalent of the law of leaving the animal until it dies.
What does "Yelchu l'Yam haMelach" mean?
Some say that it means destruction alone. According to this, "the Dead Sea" is simply an expression for the fact that no one will be able to reach the money any more, and it would be equally good to grind the silver coins into dust and throw the dust into the Mediterranean. There is no problem with this, since the entire point is that people should no longer be able to use it.
Others understand that "the Dead Sea" was said specifically about salty seas, such as the Mediterranean or the Red Sea, and it does not depend on the Dead Sea near Masada. The reason is this: if the money is thrown into streams and rivers of fresh water, people can still reach it, whereas when it is thrown into the ocean or the Mediterranean, no one will reach it any more.
In summary: in any event, the point is that the money must be removed from the world, and it is certainly forbidden ever to derive benefit from it, at the very least by rabbinic law.