Rambam - 1 Chapter a Day

These distinctions are all Rabbinic stringencies. According to Scriptural Law, if a person is pure, he is pure with regard to all circumstances (see the conclusion of Halachah 2).

I.e., something on which a zav stood, sat, or lay upon. Such an article is a primary source of impurity and imparts impurity to one who touches or carries it.

Hilchot Metamei Mishkav UMoshav 10:1. As stated there, this refers even to a person who is an observant Jew. Since he is unaware of the intricacies of the laws of purity, we fear that he contracted impurity without realizing that he did so.

Which must be eaten in Jerusalem in a state of ritual purity (Hilchot Ma'aser Sheni 3:1).

The term literally means “those who are set apart,” for these people would avoid contact with ordinary people lest they become impure. See Hilchot Tum’at Ochalin 16:12. This is the source of the term Pharisees found in secular literature describing the Talmudic period.

Since terumah is referred to as kodesh and there are more severe laws regarding its impurity than the second tithe, our Sages imposed greater stringencies regarding it.

Hilchot Parah Adumah 13:7.

See also Hilchot Mikveot 1:8.

From the Rambam’s Commentary to the Mishnah (Zavvim 5:12), one might conclude that there is a problem even with regard to touching terumah unless one immersed with that intent.

See Hilchot Mikveot 1:8, 9:17.

I.e., in a situation where only his hands become impure, as mentioned in ch. 8.

Since, generally, a person’s hands are considered as impure, one must wash one’s hands before partaking of the second tithe. This ruling is evident from the Rambam’s Commentary to the Mishnah (Chagigah 2:5). There are, however, several other places in the Rambam’s works from which one might conclude that such a washing is not required.

This applies even if the person is certain that he did not contract impurity.

As would be required had he contracted Scriptural impurity.

And it is possible that they came in contact with a source of impurity [the Rambam’s Commentary to the Mishnah (Taharot 7:8)]. Rabbenu Asher (as quoted by the Kessef Mishneh) asks: If so, seemingly, the person should be required to immerse his entire body?

In contrast to the instance mentioned in the first clause, in this situation, the person does not know that he did not contract impurity.

For according to Scriptural Law, unless a person knows with certainty that he is impure, he is not required to immerse himself.

Shabbat 15b.

Where they are unlikely to be touched by people.

Accordingly, it would appear that the ashes of the red heifer must also be sprinkled upon them. This conclusion is borne out by Hilchot Metamei Mishkav UMoshav 11:12.

In contrast to the previous halachah.

That position would indicate that they were impure and were being taken there to be immersed.

Hilchot Metamei Mishkav UMoshav 11:12.

The day the Paschal sacrifice was offered. Since all the pilgrims to the Temple would be offering their sacrifices that day, it was likely that the knife was brought for that purpose and immersed beforehand so that it would be pure.

Were the knife to be impure, the sacrifice would be disqualified. Even so, the Sages did not suspect that they contracted impurity [the Rambam’s Commentary to the Mishnah (Shekalim 8:3)]. This leniency is particularly relevant on the Sabbath, because if the sacrifice was not acceptable, one is considered to have violated the Sabbath laws by slaughtering.

For as stated in Hilchot Metamei Mishkav UMoshav 11:9, it is assumed that even the unlearned purified themselves on the festivals.

I.e., we assume the purification process for the knife had already been started and must be completed. Therefore the knife may not be used until after nightfall on the thirteenth. The knife should not be immersed on the festival itself, because that is forbidden by Rabbinic decree (Hilchot Sh’vitat Yom Tov 4:17).
The Ra’avad forcefully differs with the Rambam’s ruling. Nevertheless, the Kessef Mishneh substantiates the Rambam’s understanding.

We assume that it was discharged by an unlearned person who is considered as a zav whose saliva is impure.

Individuals who maintain a state of ritual purity at all times (Halachah 1).

If, however, the reason the primary source is considered impure is a Rabbinic decree, when there is a question whether consecrated food or terumah touched that primary source, the consecrated food or terumah is not burnt. This follows the general principle: A doubt concerning a matter of Scriptural Law is judged stringently. A doubt concerning a matter of Rabbinic Law is judged leniently.

Consecrated food and terumah that are pure are not permitted to be destroyed without reason. Nevertheless, because there is a question concerning their purity, it is permitted—indeed, deemed necessary—to burn them.

For there is a question whether they contracted impurity and it is forbidden to partake of these foods if they are impure.

For, as stated above, consecrated food and terumah that are pure are not permitted to be destroyed purposelessly. In such a situation, terumah is left until it definitely contracts impurity (Hilchot Terumah 12:3) or until it rots. Consecrated foods are left until one of the above occurs or they are disqualified because of the passage of time.

Since the laws concerning consecrated foods are more stringent than those concerning terumah, if a situation warrants that terumah be burnt, certainly, consecrated foods should be burnt (Kessef Mishneh).

E. g., as described in the following halachah, there is a question whether or not the food touched a beit hapras. Since a beit hapras itself is impure only because of a doubt and there is a doubt whether it touched the beit hapras, the situation is considered one of compounded doubt. In that instance, we rule leniently and do not burn the food. Nevertheless, the doubt is considered serious enough to prevent the food from being eaten.

Since burning consecrated food is more severe than burning terumah, it is appropriate to say “needless to say” in this instance (Kessef Mishneh).

This ruling applies in a private domain. If such a situation would arise in a public domain, the food would be considered as pure [the Rambam’s Commentary to the Mishnah (Taharot 4:5)].

A field containing a grave that was plowed and the bones of the corpse were lost in its earth (Hilchot Tum'at Meit 2:16, 10:2).

Since the gentile nations are not always careful about burial, we fear that some bones from a corpse might have unknowingly been mixed in the earth (ibid. 2:16).

As stated in Hilchot Metamei Mishkav UMoshav 10:1, because of his unfamiliarity with the laws of impurity, such a person and his clothes are deemed impure.

As mentioned in Halachah 4 above.

It must, however, be known that the person is impure. If not, there is another element of doubt involved and a more lenient ruling is warranted (Rambam LeAm).

See Hilchot Metamei Mishkav UMoshav 2:6 where the basis for this ruling is explained.

For in none of these instances is it definitely established that impurity was present.

I.e., another entity touched one of the six and thus became impure, that entity touched another entity and the third entity touched the terumah.

This is a situation of compounded doubt, as mentioned in Halachah 12.

In Halachah 12. Generally, if there is a doubt whether or not terumah contracted impurity, the ruling is held in abeyance. Only when it has definitely contracted impurity is it burnt. In these six instances, our Sages were stringent and considered the initial questionable situation (the beit hapras, the earth from the Diaspora, etc.) as definitely impure and calculated the doubts accordingly.