We have learned previously (see the Mishna on 24b), that an am ha’aretz – a simple person who is not always careful about the rules of ritual purity – can be relied upon to attest to the purity of kodashim (Temple sacrifices), and, under certain circumstances, even to the purity of teruma (tithes). The Mishna on our daf repeats this teaching, and extends it to the city of Jerusalem generally and the period of the pilgrimage festivals specifically, when everyone is trusted even with regard to teruma. Rabbi Yehoshua ben Levi quotes a passage from Sefer Shoftim (20:11) as a source for this, which teaches how all Jews when gathered together are considered to be haverim – friends, like one man united. The Talmud Yerushalmi quotes another source, this one from (124:3), which teaches that the city of Jerusalem is united at the time when the tribes all travel there. Aside from these quotes, the Rambam teaches that this ruling is based on the assumption that everyone prepares himself for a visit to the Temple by first immersing in a mikveh properly, recognizing that sacrificing a korban demands ritual purity. The Tosefot Yom Tov points out that the pesukim (verses) are no more than hints, and the Rambam’s explanation is necessary to understand why everyday rules are ignored in this specific time and place.
Once Yom Tov is over, all of the normal rules once again come into effect, and the Temple utensils that were used during the holiday were all taken out to be immersed in the mikveh to ensure that they are tahor (ritually pure), given the fact that amei ha’aretz – people whose care and concern with the rules of ritual purity are suspect – had been in the area of the mikdash throughout the holiday. One exception mentioned in the Mishna is the shulhan – the table that held the lehem hapanim (the show bread) – which could not be taken out to be immersed since it was always in use (see 25:30). Therefore anyone walking into the area of the shulhan throughout the holiday – or even after it was over, when the area was being cleaned up – was warned not to touch it, lest it become ritually defiled.
Two other exceptions were the inner and outer altars, which – as explained by Rabbi Eliezer – were connected to the ground and as such were not considered movable vessels that could become tameh.