Mishnayos Zavim Perek 5 Mishnah 12

אלו פוסלים את התרומה – from/according to the Rabbis. And all of it is from the eight things that they decreed בו ביום/on that selfsame day (that Rabban Gamaliel was deposed as the head of the Sanhedrin -see Talmud Berakhot 28a [see the Bartenura commentary to Tractate Shabbat, Chapter 1, Mishnah 4, also Tractate Shabbat 13b – our Mishnah lists nine of the fourteen of them], except for [the law regarding] the טבול יום/the one who immersed himself that day which is from the Torah.

האוכל אוכל (he who eats food) – that is first degree of ritual defilement or second degree of ritual defilement, they decreed that his body is second degree of ritual defilement, and it invalidates the heave-offering/priest’s due with his contact, touching, for second degree of ritual defilement makes priest’s due/heave-offering unfit.

והשותה משקים טמאים – it becomes also second degree of ritual impurity, and makes the priest’s due/heave-offering unfit/invalid, and the reason that the Rabbis decreed on these, is that sometimes, when a person eats unclean foods and pours liquid of heave-offering in his mouth while the foods are impure in his mouth, and invalidates them. And also, sometimes that he drinks impure liquids and pours foods of heave-offering/priest’s due in his mouth while they are still in his mouth, invalidating them.

והבא ראשו ורובו – after he immersed [in a Mikveh[ on that same day.

במים שאובין – because they would immerse in the badly smelling/decaying waters of caves and they would put upon them afterwards drawn waters to remove to bad-smelling/decaying waters, they began and made a fixed rule to state that the waters of caves do not purify but rather [only] drawn waters purify; they (i.e., the Rabbis) stood and decreed defilement upon them [who used those waters], for perhapsthey would come to annul the law of Mikveh and immerse in drawn waters, and in order to fulfill this decree to establish it, they added to it and decreed on a person completely pure who had three LOG of drawn waters that fell upon him, that he would invalidate the heave-offering/priest’s due until he immersed [in a ritual bath].

והספר – all Holy Writings/Scrolls defile the priest’s due/heave offering through contact. Because at the outset, they would hide food of priest’s due/heave offering next to a Torah Scroll saying “this is Holy and that is Holy,” since they saw that Scrolls would come to loss, that the mice that are found near the food would ruin/cause loss to the Scrolls, they decreed on the Torah, Prophets and Writings (i.e., the three portions of Scripture) would defile the priest’s due/heave-offering through their contact.

וטבול יום – invalidates the priest’s due/heave-offering from the Torah until his sunset arrives. But this is not from the eighteen decrees that they (i.e., the Rabbis) decreed on that day (see the Bartenura commentary to Tractate Shabbat, Chapter 1, Mishnah 4).

והאוכלים – that were defiled by liquids. The Sages decreed on the liquids that were defiled by second degree of ritual impurity, to become first-degree, and that they would defile the foods. It is a decree because liquids that come on account of a defiling reptile/insect which are first-degree according to the Torah. But why did not decree on foods also to become first-degree? It is a decree because of foods that come on account of an insect/defiling reptile, because the foods require fitness to become unclean (which arises from contact with certain liquids), but they are not susceptible to receive defilement other than through coming in water, but the liquids are liable/likely to be susceptible to receive defilement and do not require fitness to become unclean nor repair, and their defilement is found more.

וכלים שנטמאו במשקין – that according to the Torah, even if the liquids were defiled by a reptile/insect (i.e., creeping animal), they do not defile vessels, for humans and vessels are not susceptible to receive ritual defilement other than from a primary source of ritual impurity, but the Rabbis decreed that even on liquids that were defiled on account of hands which are second-degree of ritual impurity, that they would defile vessels, as a decree because of the liquid of a person with gonorrhea/זב or a woman with a flux/זבה, as for example, their spittle and their urine, which are a primary source of ritual impurity and defile vessels according to the Torah.