Shekalim 1:4-5
Shekalim 1:4
Rabbi Yehuda said that Ben Buchri testified in Yavne that if a kohein contributes the half-shekel, he has not sinned (i.e., it is voluntary for kohanim). Rabbi Yochanan ben Zakkai disagreed, saying that if a kohein does not contribute, he has sinned (i.e., it is obligatory). The kohanim expound the verse “Every flour offering of a kohein must be burned; it shall not be eaten” (Leviticus 6:16) for their own benefit (i.e., to exempt them from paying the half-shekel). The omer offering, the showbread and the two loaves are all flour offerings and they are eaten (therefore they do not belong to the kohanim. These things are paid for with the half-shekel, so kohanim must be exempt from contributing).
Shekalim 1:5
Even though they would not take collateral from women, children or slaves, if these people contributed a half-shekel, it was accepted. If a non-Jew or a Samaritan (quasi-Jew) contributed a half-shekel, it was not accepted. Also not accepted from non-Jews and Samaritans: birds for the offering of a zav, a zavah or a woman after childbirth, sin offerings and guilt offering, but they did accept offerings from vows or gifts. The general rule is that anything that may be vowed or donated may be accepted from non-Jews and Samaritans; anything that may not be vowed or donated may not be accepted from them. Ezra outright told the Samaritans of his day, “It is not for you and for us to build a house for our God” (Ezra 4:3).