Nazir Chapter 8, Mishnah 1. Before us is a particularly long and complex mishnah dealing with a case of doubtful nezirus - a doubt as to which nazir became tamei, and how the two nezirim practically fulfill their obligations.
The case in the mishnah:
"Shnei nezirim she'amar lahen echad: ra'isi echad mikem shenitma, v'ein yodea eizeh mikem" - two men accepted upon themselves a vow of nezirus, and a man came and told them that he saw that one of them became tamei, but he does not know which of the two it was.
The Gemara clarifies the details of the case:
The location of the sighting: the nezirim were standing in a private domain, and the witness was not with them but rather observed from a distance. For if three had been together, the place would be considered a public domain, and a doubtful tumah in a public domain is tahor, and we would have said that both of them are tahor. But here we are dealing with a doubtful tumah in a private domain, and therefore we must be stringent with both of them.
"V'ein yodea eizeh mikem": the nezirim themselves are silent and express no opinion, or they themselves also do not know. In this case we believe the witness who saw that one of them became tamei, only that it is not known who it is.
Resolving the doubt when both nezirim are alive:
"Megalchin u'mevi'in korban tumah v'korban taharah" - first both of them complete the days of their nezirus, since the one who is tahor cannot shave his head until he completes his nezirus. After completing it they shave, one of them as a tamei nazir and the second as a tahor nazir.
And these are the offerings that they bring:
The offering of tumah: two birds - one as a chatas and one as an olah - and a lamb as an asham.
The offering of taharah: a ewe as a chatas, a male lamb as an olah, and a ram as shelamim.
And they stipulate with one another: "Im ani hu hatamei - korban tumah sheli v'korban taharah shelcha, v'im ani hu hatahor - korban taharah sheli v'korban tumah shelcha" - if I am the one who is tamei, the offering of tumah is mine and the offering of taharah is yours, and if I am the one who is tahor, the offering of taharah is mine and the offering of tumah is yours.
"V'sofrin shloshim yom" - afterward they count another thirty days. We are dealing with a nezirus of thirty days, which is the standard nezirus, and in it the case is simpler. The need for this count stems from the fact that one of them was a tamei nazir, and a tamei nazir, after bringing the offering of his tumah, must count thirty days for the nezirus of his taharah.
"U'mevi'in korban taharah" - and at this stage they bring only an offering of taharah, and they say: "Im ani hu hatamei - korban tumah sheli v'korban taharah shelcha, v'zehu korban taharasi" - if I am the one who is tamei, the offering of tumah is mine and the offering of taharah is yours, and this is the offering of my taharah, meaning that the offering we are bringing now after the second shaving is the offering of my taharah; "v'im ani hu hatahor - korban taharah sheli v'korban tumah shelcha, v'zehu korban taharascha" - and if I am the one who is tahor, the offering of taharah is mine and the offering of tumah is yours, and this is the offering of your taharah.
A case in which one of the nezirim died:
Up to this point the solution is simple and orderly. The difficulty arises in the case of "mi shemes" - if one of the nezirim died before they managed to bring the first set of offerings. The nazir who remained alive is in a state of doubtful tumah, and he cannot make a stipulation regarding the offerings and say that he is tamei or tahor, since he cannot do both.
"Amar Rabbi Yehoshua: yevakesh echad min hashuk sheyidor kenegdo b'nazir" - he should ask a man from the marketplace to vow nezirus corresponding to his, and he says to him: "Im tamei hayisi - harei atah nazir miyad, v'im tahor hayisi - harei atah nazir achar shloshim yom" - if I was tamei, you are a nazir immediately, and if I was tahor, you are a nazir after thirty days.
"V'sofrin shloshim yom u'mevi'in korban tumah v'korban taharah" - and the nazir whose status is in doubt says to the man whom he brought into nezirus with him: "Im ani hu hatamei - korban tumah sheli v'korban taharah shelcha" - if I am the one who is tamei, the offering of tumah is mine and the offering of taharah is yours, for I said that if I am tamei your nezirus begins immediately, and now you have completed your nezirus and you must bring an offering of taharah. "V'im ani hu hatahor - korban taharah sheli" - and if I am the one who is tahor, the offering of taharah is mine, for I said that your nezirus only begins now, and the offering we are bringing now is mine, "v'korban tumah b'safek" - and the offering of tumah is brought on account of the doubt.
And how can an offering of tumah be brought out of doubt?
The bird chatas: it can be brought on account of a doubt, since it is not eaten.
The bird olah: it can be brought conditionally - if he is obligated, it counts toward the obligation of his nezirus, and if not, it is a voluntary offering.
The asham: an asham is not brought on account of a doubt.
And a tamei nazir, once he has brought the chatas, may begin the nezirus of his taharah, for the olah and the asham do not prevent him from beginning it.
"V'sofrin shloshim yom u'mevi'in korban taharah" - and he says: "Im ani hu hatamei - korban tumah sheli v'korban taharah shelcha" - if I am the one who is tamei, the offering of tumah is mine and the offering of taharah is yours, for I said that if I am tamei you would be a nazir immediately, and the offering of taharah that was brought thirty days ago was yours, "v'zehu korban taharasi" - and this is the offering of my taharah, for I brought an offering of tumah, counted thirty days of a nezirus of taharah, and now comes the offering of my taharah. "V'im ani hu hatahor - korban taharah sheli" - and if I am the one who is tahor, the offering of taharah is mine, the first offering of taharah was mine, and the offering of tumah brought then was on account of the doubt, "v'zehu korban taharascha" - and this is the offering of your taharah, for I said that if I am tahor your nezirus begins after thirty days.
The approach of Ben Zoma:
"Amar lo Ben Zoma: umi shomea lo sheyidor kenegdo b'nazir?" - who will agree to do him such a great favor and accept nezirus upon himself? This is too much to expect, and he will not find anyone who will agree to it.
"Ela mevi chatas ha'of v'olas behemah" - therefore the nazir who remains in his doubt should handle it himself, and instead of a full set of offerings he brings one offering that addresses each of the possibilities. First he brings a bird chatas and an animal olah, and says: "Im tamei hayisi - hachatas mechovasi v'ha'olah nedavah" - if I was tamei, the chatas is part of my obligation and the olah is voluntary, for the chatas is among the offerings of tumah that I am obligated in, and the olah is not for the nezirus but voluntary. "V'im tahor hayisi - ha'olah mechovasi v'hachatas b'safek" - and if I was tahor, the olah is part of my obligation and the chatas is on account of the doubt, for the olah comes upon the completion of my nezirus (and he does this after thirty days), and the chatas remains a matter of doubt - and indeed a bird chatas may be brought on account of a doubt, and it is not eaten.
"V'sofer shloshim yom u'mevi korban taharah" - he counts another thirty days, and then he can bring the complete offering of taharah, all the offerings of taharah, and he says: "Im tamei hayisi - ha'olah harishonah nedavah v'zo chovah" - if I was tamei, the first olah was voluntary and this one is obligatory, for the first olah was brought at a time when I was tamei and it was the chatas that counted toward my obligation, and now that I have finished my nezirus I am obligated in an olah. "V'im tahor hayisi - ha'olah harishonah chovah v'zo nedavah" - and if I was tahor, the first olah was obligatory and this one is voluntary, for the olah that I brought thirty days ago is the one that counted toward my obligation, and this one now is voluntary, and the first chatas was likewise on account of the doubt, and the rest of the offerings I bring now.
Rabbi Yehoshua responded to him: according to this approach, it turns out that he brings his offerings in two parts - the olah was brought thirty days ago and the rest of the offerings are brought now, thirty days later; whereas according to Rabbi Yehoshua's approach, in which there is an additional person who vows along with him, all the offerings can be brought together.
However, the Gemara notes that there is no problem at all in bringing the offerings separately in this manner, and Rabbi Yehoshua said what he said only in order to sharpen the students and stimulate them to think. And the mishnah concludes that they conceded to Ben Zoma: there is no impediment to dividing the offerings, and there is no need to persuade a third party to join in nezirus.
In summary: in this mishnah we learned the law of two nezirim about whom a man testified that one of them became tamei but it is not known which - a doubtful tumah in a private domain, in which we must be stringent with both of them. The solution: they complete the nezirus, shave, bring an offering of tumah and an offering of taharah with a stipulation between them, count thirty days and bring an offering of taharah with a further stipulation. In a case where one of them died, Rabbi Yehoshua held that he should ask a man from the marketplace to vow nezirus corresponding to his and stipulate with him; and Ben Zoma responded that no one will be found who agrees, and therefore he himself brings a bird chatas and an animal olah conditionally, counts thirty days and brings the offering of taharah - and this is the halachah, like Ben Zoma.