Parah 3:6 - 3:7

וכיפה כנגד האוטם (and an arch corresponding to the foundation/substructure -filled with earth) – the feet of the arch that the arch is supported on them is called an אוטם/foundation. But the legs of the upper arch do not correspond with the legs of the lower [arch] but rather correspond to the arch itself, that opposite the upper foundation stands the lower cavity.

מפני קבר התהום – so that there would not be there pressed ritual impurity which bursts forth and rises.

ופרה וכל מסעדיה – those who support and aid it. It is the language of (Psalms 41:4): “The LORD will sustain him on his sickbed.” But even though the heifer is not susceptible to receive defilement while alive, they made a greater preference with it.

ולא אדומה – they would not remove another red cow/heifer with her on the ramp/causeway.

שלא יאמרו שתים שחטו – for the All-Merciful said (Numbers 19:3): “[You shall give] it (i.e., one cow) [to Eleazar the priest. It shall be taken outside the camp [and slaughtered in his presence],” but not her and her fellow [cow].

ובית טבילה היה שם – and that same house for immersion also was hollow on top of arches because of the grave in the depth (i.e., a covered-up uncleanness discovered). But even the place of its pile of wood on the altar of the Temple and its pit that are taught further on (see Mishnayot 9 and 10 of this chapter), all of them were on top of arches.

ומטמאים היו את הכהן – in that they would place their hands upon him, as it is taught in the Mishnah further on (see Mishnah 8 of this chapter), through this he would become defiled, for the clothes of those who consume Holy Things are unclean through treading/leaning against to the heifer of a sin-offering. But Maimonides explained that they would defile him with a creeping thing or with other defiling things that defile with ritual impurity until the evening.

במעורבי שמש היתה נעשית – that they (i.e., the Sadducees) would expound (Numbers 19:9): “A man who is pure shall gather up [the ashes of the cow and deposit them outside the camp in a pure place, to be kept for water of lustration for the Israelite community],” there isn’t someone pure other than someone whose sun has set, and similarly it states (Leviticus 22:7): “As soon as the sun sets, he shall be pure, [and afterward he may eat of the sacred donations , for they are his food].” But the Sages received the teaching that [the word] “pure” that is stated in the portion of the sin-offering (I.e., Numbers 19:9, see above) it is stated is pure for tithes, which is a טבול יום/one who immersed himself that day.