Shekalim Chapter 7, Mishnah 2. We continue with the subject we began in the previous mishnah: coins that were found, and how to determine where they came from - whether they have the status of chullin (ordinary money) or of Maaser Sheni.
"Maos shenimtze'u lifnei socharei behemah - le'olam maaser" - Coins found in front of cattle dealers are always maaser:
Coins found in front of the dealers who sell animals in Jerusalem have the status of Maaser Sheni always, both during the festival, when everyone comes up to Jerusalem, and during the rest of the year. The mishnah's assumption is that coins lying in front of the animal sellers are Maaser Sheni coins, with which people would buy animals to eat in Jerusalem.
And why is this so even during the rest of the year? Because the festival pilgrims would bring Maaser Sheni coins with them, and when they were left with more than they needed for the days of their stay in Jerusalem, they would leave the remainder with their relatives in Jerusalem, and those relatives would spend these coins throughout the year.
And why do we not assume that the coins fell from the animal sellers themselves? After all, once the sellers received the coins they became chullin, since the sanctity of the Maaser Sheni passed over to the animals. The reason is that the buyers outnumber the sellers, and since the customers are more numerous than the dealers, we assume that the coins came from the buyers and not from the sellers - and therefore the sanctity of Maaser Sheni is still upon them.
"B'Har HaBayis - chullin" - On the Temple Mount they are chullin:
Coins found on the Temple Mount itself have the status of chullin. This ruling applies even during the festival, when most of the coins people are carrying are Maaser Sheni coins, because we follow the majority of the days of the year, during which most people are not holding Maaser Sheni coins.
Coins found in Jerusalem (not in front of cattle dealers):
"Bish'as haregel" - during the festival - maaser: Coins found in Jerusalem during the festival have the status of Maaser Sheni, since at that time maaser coins are found in everyone's possession.
"Bish'ar kol yemos hashanah" - during the rest of the days of the year - chullin: Since this is the majority of what people are carrying during the rest of the year.
And why do we not follow the rest of the year here, as we did on the Temple Mount? Because the practice was to sweep the markets of Jerusalem, where these coins were found, every single day, so any coin lying there would be found. Since the markets were swept, we cannot assume that the coins remained there from earlier in the year.
The Temple Mount, by contrast, does follow the rest of the year, since they did not sweep it: because it is a high place exposed to the winds, there is no need to sweep it in practice. But coins would remain there, and therefore it is possible that they are from the rest of the year - unlike in Jerusalem.
In summary: Coins found in front of cattle dealers are always maaser, because the buyers outnumber the sellers, and because maaser coins were deposited with the relatives of the festival pilgrims and spent throughout the year. On the Temple Mount they are chullin, even during the festival, because we follow the majority of the days of the year, since the Temple Mount is not swept and coins remain there. And in Jerusalem, during the festival everything is maaser, since at that time maaser coins are found in everyone's possession, and during the rest of the year they are chullin, in keeping with the majority of coins people carry during the rest of the year.