(Mishnah): Standing corn can save a sheaf and other standing corn; a sheaf cannot save another sheaf nor standing corn.

When does standing corn save a sheaf? If it was not forgotten, even if it is one stalk.

A Se'ah of plucked corn and a Se'ah of unplucked corn; and the same applies to fruit trees, garlic and onions - cannot combine (to count them as two Se'ah).

(R. Yosi): If anything of the poor man intervenes, they do not combine; otherwise, they do combine.

(Gemara) (Rebbi): (Why does standing corn save sheaves?) The pasuk states (Devarim 24:19), "When you shall reap your harvest in the field and you shall forget a sheaf in the field" - it is only a sheaf that has cut stalks around it but not standing grain around it that can become Shichechah. Why is this? Only when it's all cut is it called a field, but if some grain is still standing, what is underneath it is just called straw, so it is all considered like standing crop and it can save.

(Baraisa) (Rebbi): Another person's standing crops can save his crops; a gentile's crops can save a Jew's crops; wheat can save barley.

(Chachamim): Only a person's own crops save and it can only save its own type.

(Baraisa) (Rabban Shimon ben Gamliel): Just as standing crops save sheaves, so sheaves save standing crops. It is a Kal Vechomer deduction - if standing crops, that the poor have significant claim on (as the three gifts of Leket, Shichechah and Peah are taken from them), and if he forgot them, other standing crops that he did not forget save them; then sheaves, that the poor do not have such a claim on (as only Shichechah is given from it), should certainly save the standing crops!

(Rebbi to Rabban Shimon): (Rejecting this Kal Vechomer) Just because standing crops save the sheaves because the poor do not have significant claim on them, should sheaves be able to save standing crops that the poor do have significant claim on?

From both opinions we learn that sheaves can save sheaves but standing crops cannot save standing crops.

Question: (The Mishnah taught - 'When does standing corn save a sheaf? If it was not forgotten, even if it is one stalk.') This means that if it was forgotten, even if the sheaf was saved, it can return to being Shichechah. (This same question was raised earlier (Perek 5 Halacha 2 - Zevachim 49(a)) and answered from a Baraisa. Surely our Mishnah also answers the question?)

Answer: This wording of our Mishnah excludes when he first forgot the standing crops and then the sheaf - in that case, the sheaf is not saved.

(The Mishnah taught that a Se'ah of plucked corn and a Se'ah of unplucked corn...cannot save). This implies that if they were each a Se'ah and both were plucked, they would (combine and) belong to the owner. The Mishnah follows Rabban Gamliel (above Zevachim 60(d)) that two sheaves that combine to be two Se'ah are not Shichechah. (Rabbanan there say that the two Se'ah must be in one sheaf for it not to be Shichechah.)

Proof: Even if they do not combine, the unplucked corn is a standing crop, so why can't it save the sheaves? This shows that if something that could have saved was forgotten, it is Shichechah.

Rebuttal (R. Yona): (The Mishnah is discussing when) he harvested a row and forgot some standing crops and then gathered and forgot some sheaves - so he had already forgotten some standing crops before he had begun forgetting the sheaves.

Question: (R. Yosi said in the Mishnah that if anything of the poor man intervenes, they do not combine.) Does it mean that there is actually something that intervenes (such as Leket of the poor man) or even if something could potentially intervene because the sheaves are not touching each other...?

Answer (Baraisa): (An example of R' Yosi's law is) if there is grain planted next to a vineyard (and when he harvests the vineyard, Peret falls next to the grain.) Grains and grapes are not harvested at the same time (of year), but it is still the Baraisa's example of R. Yosi's law - this shows that it applies even if it could only potentially intervene.