Shekalim, Chapter Two, Mishnah Three
This mishnah discusses various scenarios in which a person set aside some money to use for his shekel or for another sacrifice and after he counted up the money he had set aside there was a surplus. The question is whether or not the surplus money is sacred and therefore must be used for a free-will offering.
1) One who gathered some coins and said: Behold, these are for my shekel.
a) Bet Shammai say: the surplus [is used to purchase] freewill-offerings.
b) But Bet Hillel say: the surplus is non-sacral property.
2) [If he said:] From them I shall bring my shekel, they agree that the surplus is non-sacral property.
3) [If he said]: These [coins] are for a sin-offering, they agree that the surplus [goes to the chests of] freewill-offerings.
4) [If he said]: From these I shall bring a sin-offering, they agree that the surplus is non-sacral property.
Section one: The person gathered some coins together and declared that he would use them to bring his shekel. It turned out that there was more than a shekels worth of coins there. Bet Shammai say that since they had been set aside to give to the Temple, they are sacred and therefore they must be used to purchase free-will offerings. Bet Hillel, on the other hand, hold that the surplus is not sacred because when he collected the money his intention was that only a shekels worth of the coins should be given to the Temple.
Section two: In this case, instead of saying These are for my shekel he says From them I shall bring my shekel. It is clear that his intention is to use only whatever adds up to a shekel and therefore Bet Shammai agree that the surplus is not sacred.
Section three: In this case Bet Hillel agree with Bet Shammai that the surplus is sacred. Tomorrows mishnah will explain the difference between shekels and sin-offerings such that Bet Hillel agrees in the case of the latter.
Section four: This is the same rule as in section twoas long as he says From these I will bring . the surplus is not sacred.