Pesachim 72 - 78
Shankbone versus Egg
On Pesach eve our Seder Plate includes the zeroa, a broiled shankbone or other piece of meat, which serves as a remembrance of the Pesach sacrifice which was broiled and eaten on this night in the time of the Beis Hamikdash. We don't eat the zeroa until the next day (or the daytime meal of the second day outside Eretz Yisrael if it is to be used at the second Seder) because the mishna (Pesachim 53a) tells us that the custom in some places is to refrain from eating any broiled meat on Pesach eve. The reason for this custom is to avoid giving the impression that we have offered an animal as a sacrifice (which is forbidden when there is no Beis Hamikdash) and that we are eating its flesh in the prescribed manner of broiling.A beraisa cited in our gemara defines the ban on eating a broiled lamb or kid on Pesach eve as applying only to an animal that has been broiled in its entirety, without any part of it separated before the broiling began. Rashi explains that this is the ban referred to in the aforementioned mishna, and that it is limited to those places where the custom is to refrain from eating broiled meat on Pesach eve. Rabbeinu Asher, however, has a different approach, and it is his view which is cited in the Shulchan Aruch (Orach Chaim 476:1). Even in places where the custom is to eat broiled meat on Pesach eve because there is no fear that it will give the appearance of eating sacrificial flesh, it is nevertheless forbidden to broil an entire lamb or kid because this will create such an impression.
The custom everywhere today is to refrain from eating broiled meat on Pesach eve, and this extends even to those things which were not valid for the Pesach sacrifice. Anything which requires slaughtering (beef or fowl) is included in this ban, but fish and eggs are not included. It is therefore customary to eat on Pesach eve the egg on the Seder Plate, which is a remembrance of the Chagigah sacrifice offered together with the Pesach one in certain circumstances, even if it has been broiled.
The Gift and the Service
One evening Rabbi Tarfon did not come to the Beis Hamidrash together with the other sages. In the morning Rabban Gamliel, the head of the Sanhedrin, asked him the reason for his absence.
Rabbi Tarfon, a kohen, responded that he was busy performing his priestly service.
This struck Rabban Gamliel as very strange because they lived after the destruction of the Beis Hamikdash, so what sort of priestly service could Rabbi Tarfon possibly have been performing?
In response Rabbi Tarfon quoted the passage (Bamidbar 18:7): "I shall give you your priesthood as a gift of service and the stranger who approaches it shall die."
The Torah, he explained, equated the gifts which Hashem delegated to the kohanim such as the tithe of terumah with the service performed in the Beis Hamikdash. Rabbi Tarfon had been busy eating terumah the night before and he referred to it as a performance of priestly services.
It is interesting to note that the concluding words of the passage he quoted serve as a perfect illustration of this equation. A stranger, i.e., a non-kohen, who performs the sacrificial service in the Beis Hamikdash is punished by an early death at the hands of Heaven. The same punishment is due for a non-kohen who eats terumah. The Torah's warning against a non-kohen intruding upon the areas reserved for the kohen is thus directed at such usurpation both of his gift and of his service.