Mishnayos Nazir Perek 9 Mishnah 2

נזיר שגלח – he brought his sacrifices and cut his hair/shaved upon them and afterwards it became known to him that he had become ritually unclean/impure during his days of Naziriteship.

אם טומאה ידועה – an impurity that it was possible that it was known such as the case of it was not the grave in the depth (i.e., a covered – up uncleanness discovered – In the Jerusalem Talmud Nazir 57f, it is asked? What is a grave of the depth? A corpse buried in stubble, straw, earth, or pebbles, but if buried in water, it does not make a grave of the depth – i.e., it does not make unclean that which was above it before discovery; or, a grave that nobody remembers to have existed).

סותר – and he returns and counts another [period] of Naziriteship.

טומאת התהום אינו סותר – if it became known to him that in the place that he passed was defilement in the depth, but it is a defilement that no one recognizes it even to the end of the world, even though he certainly was ritually impure, he does not lose [the days he had already counted], for such is the Halakha concerning a Nazirite.

אם עד שלא גלח – a shearing in purity even if he had already brought his sacrifices, for since it became known to him prior to his shaving/cutting his hair.

בין כך ובין כך – whether it is a known defilement whether it is a defilement of the depth, he loses [the days that he had counted in fulfillment of his Nazirite vow] for it is derived that defilement of the depth does not cause loss [of the period counted in fulfillment of his Nazirite vow] specifically after his shaving/cutting his hair in spiritual purity.

כיצד – the law of defilement of the depth.

ירד לטבול במערה – for he was defiled through the defilement of an unclean reptile, or another defilement of a similar nature which is not from a dead person, and he went down to immerse from his defilement, and it was found [there] an olive’s bulk from a dead person floating on the face of the water and it is uncertain/doubtful whether he became defiled through it or he was not defiled, he is impure, but we hold that an uncertain/doubtful defilement floating on top of the water is pure, but these words regard the defilement of an unclean reptile. But regarding the defilement through contact with the dead, he is impure, and if this uncertainty/doubt was known to him after he had cut his hair/shaved, he is impure, for this is known defilement, for since he was in a place where it was possible that people would see him. And that which it (i.e., the Mishnah) took [linguistically] that he went down to immerse, it is something remarkable that is being taught to us, for even though that a person who immerses from his defilement to ritual purity is warned from all things that defile, even so, he is defiled.

נמצא משוקע בקרקע המערה – in the place that he immersed and he has certainly become defiled. If it became known to him after he shaved/cut his hair, he is pure, and he doesn’t lose [any of the time of his vow as a Nazirite] for this is the defilement of the depth which was in a place where it was not known to any person.

ירד להקר טהור – even though he went down to cool off and chill himself, but he did not go down to immerse in order that he would be careful from defilement, even so, he is ritually pure, if he was not defiled through contact with the dead, but if he did go down to purify himself from defilement from contact with the dead, and he immersed in a cave where the dead was embedded in it and he completed his Naziriteship, or was a person who was defiled by contact with the dead that had immersed, and afterwards accepted upon himself Naziriteship, he is defiled and loses [the period that he had fulfilled of his Nazirite vow] for something presumed impure is impure and something presumed pure is pure.

שרגלים לדבר – meaning to say, there is a rationale and principle to the matter to state that one does not derive a Halakha for defilement in a depth, which for a Nazirite is pure, other than when he was a Nazirites who was presumed to be pure, and when he was presumed to be impure.