(Mishnah): If two brothers divided (a field that they inherited) - each gives Peah (for his portion).

If they again became partners in the field, they give one Peah (for the entire field).

If two people bought a tree, they give one (portion of) Peah.

If one bought the northern side and one bought the southern side, each gives Peah for his portion.

(Gemara): If they harvested half the field as partners and then divided the field; the first does not need to give Peah for the second, even for what was harvested earlier, since they ultimately divided, it is considered like two fields from the beginning.

If they again became partners and harvested, (it is considered one field for that new harvest and) he must give Peah for the second one's portion of their harvest as well, although not for the second one's portion of the first half.

(R. Yochanan): If they were partners in half the field and he harvested the first half of that half, and before he harvested its second half, they became partners in the second half of the field, and he harvested the rest of the field, he may give Peah from the first quarter on the second quarter (since they were originally partners in that first half of the field). Alternatively, he may give from the second quarter for the second half (since when he harvested that second quarter, they were partners in the second half). However, he may not give from the first quarter for the second half.

If half of one's field had reached a third of its growth (and had become obligated in Peah) and the other half had not - if he had first harvested the first half of that (first) half and before he managed to harvest its second half (i.e. the second quarter), the second half of the field reached a third, and he then harvested the rest of the field - he can give from the first quarter on the second quarter or from the second quarter on the second half, but not from the first quarter on the second half.