A brand-new concept, -טוּמְאַת תְּהוֹםtumat tahom TB Nazir 63

Today’s daf TB Nazir 63 introduces a brand-new concept, -טוּמְאַת תְּהוֹםtumat tahom. This term is hard to translate into English, but is readily explained. It is a person who is buried in the ground but nobody no longer knows that the body is there. This source of tumah, ritual unreadiness, is contrasted with טוּמְאָה יְדוּעָה-tumah yedu’ah.  In this case you may not know that body is buried in that spot, but somebody else does. The tumat tahom provides a leniency for the nazir.

“MISHNA: With regard to a nazirite who shaved for the conclusion of his naziriteship, and it later became known to him that during his naziriteship he was ritually impure from a corpse, if it was a known impurity, i.e., people were aware of the impurity when he became impure, he negates his entire naziriteship. And if it was ritual impurity imparted by a grave in the depths (-טוּמְאַת תְּהוֹםtumat tahom-gg), one that was unknown at the time, he does not negate his naziriteship. If he discovered he was impure before he shaved, he negates his naziriteship in either case.” (Sefaria.org translation) In other words, after the nazir has successfully completed the number of days for his nazirite vow, brought his sacrifices, and shaved his head and then learned that he walked over a grave that was tumat tahom, he remains tahor, ritually ready and doesn’t have to repeat his vow of nezirut.

The Gemara cites two possible sources in the Torah for the basis of the concept tumat tahom; however ultimately reaches the conclusion that this is just another halakha from Moses upon Mount Sinai. “Rather, it must be that the halakha of impurity imparted by a grave in the depths (-טוּמְאַת תְּהוֹםtumat tahom-gg), is learned as a tradition and not from the verses, which are cited merely in support.” (Sefaria.com translation)

Rambam poskins: “[The following rules apply when] a nazirite performed the shaving [required when completing his vow in] purity and afterwards discovered that he had contracted the ritual impurity [stemming from contact with a corpse] in the midst of the days of his vow. If he became impure due to a [the source for] impurity that was known [by others], all [of the days of his vow] are invalidated. He must bring the sacrifices [required when emerging from] impurity, perform the shaving [required when emerging from] impurity, count [the days of] another nazirite vow, and bring the sacrifices [required when completing his vow in] purity.

If he became impure due to [a source of] impurity [likened to] the depths, he does not invalidate [the days he observed]. This is a law communicated by the Oral Tradition.” (Mishneh Torah, Sefer Haflaah, Laws of a Nazir, chapter 6 halakha 16, Sefaria.org translation)