Gemara

(Mishnah): If a document '100 Zuz' above, and it says 200 below (in the recap of the document), or vice-versa, we follow what is below.

We write the top so that if a letter is erased from the bottom, we can learn from the top.

(Rav Papa): If above it says 'Sefel' and below it says 'Kefel', we follow the bottom.

Question (Rav Papa): If it says 'Kefel' above and 'Sefel' below, what is the law? (Do we follow the bottom, or) do we suspect that the 'Kuf' should be a 'Samech', and some of the ink was moved by a fly?

This question is not resolved.

Rishonim

Rif: Sefel stands for Se'ah (about 12 liters) v'PaLga (and a half). 'Kefel' stands for 'Kava (six Sa'im) v'Palga.'

Nimukei Yosef (DH Masnisin): We follow the bottom, for it is possible that he retracted. If the bottom weakens the bearer, e.g. it says that he is owed 100 (and the top says 200), we learn even from the last line, since he or his heir holds the document (we are not concerned lest the borrower changed it). We do not learn from the last line to help the bearer.

Nimukei Yosef (DH Sefel mi'Lema'alah): The question was undecided, so ha'Motzi mi'Chavero Alav ha'Re'ayah. Normally, we divide money due to a Safek. This is when it is impossible to clarify, e.g. a dead fetus is near a gored cow (and we do not know whether it miscarried before the goring, or due to the goring), or a house fell on a man and his mother (and we do not know who died first, which determines who inherits her property). Here, the judges do not know the truth (what was written). The parties to the document know, so the judges are quiet, and everyone keeps what he has.

Rashbam (166b DH Teiku): Here, Beis Din is unsure about the Halachah, so ha'Motzi mi'Chavero Alav ha'Re'ayah. When we are unsure what happened, e.g. a dead fetus is near a gored cow, or a house fell on a man and his mother, we divide money due to a Safek.

Rambam (Hilchos Malveh 27:15): If above it says 'Sefel', and below it says 'Kefel', we follow the bottom, for it is less. If it says 'Kefel' above and 'Sefel' below, we suspect that the 'Kuf' should be a 'Samech', and some of the ink was moved by a fly. He collects only the smaller measure of Kefel. The same applies to all similar cases. The bearer of the document has the lower hand.

Teshuvos Maimoniyos (Sof Sefer Mishpatim 69): When it is impossible to resolve both expressions, e.g. above it says 100 and below it says 200, we follow the bottom. When it is possible to explain that there is no contradiction, we do so. E.g. if a man gave his house to his son, and said 'as long as I live, I have power to do as I wish with my property', we say that this refers to his Metaltelim and other land. What he gave to his son is not 'my property.' We write the top, so that if a letter is erased from the bottom, we can learn from the top.

Darchei Moshe ha'Aruch (CM 42:8): If possible, we resolve the contradictory expressions even if they are far from each other (in the document), and all the more so if they are close, for it is not normal to contradict onself Toch Kedei Dibur.

The Rosh (10:11) brings the Gemara verbatim.

Poskim

Shulchan Aruch (CM 42:7): If above it says 'Sefel' (a measure containing a Se'ah and a half), and below it says 'Kefel' (a Kav and a half), we follow the bottom, for it is less. If it says 'Kefel' above and 'Sefel' below, we suspect that the 'Kuf' should be a 'Samech', and some of the ink was moved by a fly. He collects only the smaller measure of Sefel. The same applies to all similar cases. The bearer of the document has the lower hand.

Beis Yosef (DH v'Im): Whenever a monetary question is not resolved, we are stringent for the claimant and lenient for the defendant. We attribute the discrepancy to a fly, and he collects only according to Sefel. If it was a document of pardon, we do not say that a fly changed the word. Ha'Motzi mi'Chavero Alav ha'Re'ayah. R. Tam says that Sefel and Kefel are names of Kelim. Alternatively, they stand for Se'ah and a half and Kav and a half.

Sho'el u'Meshiv (4:2:220, cited in Hagahos Tur ha'Shalem 37): The Beis Yosef holds that regarding a receipt of payment the bearer has the upper hand, but if it is a receipt of pardon, the bearer has the lower hand.

SMA (21): Tosfos and the Rashbam connote that it is normal for a fly to shorten a letter (from a Kuf to a Samech), but not to elongate a letter. Therefore, if it says Kefel below, in any case we follow it. The Rambam must hold that it is normal for a fly to shorten or elongate a letter, therefore, he says that he collects Kefel because it is smaller.

Rebuttal (Taz): The Gemara said that if above it says 'Sefel' and below it says 'Kefel', we follow the bottom. If it says 'Kefel' above and 'Sefel' below, do we suspect that the 'Kuf' should be a 'Samech', and some of the ink was moved by a fly? This implies that in the first case, there is no Safek about a fly. Surely the bottom said Kefel, and we follow this whether a fly changed the top to Kefel, or if the top said Sefel and he retracted below. Also, in Sotah (20a) R. Meir said 'I am concerned lest a fly (rest on and) remove the ink at the extension of a Dalet, making it a Reish! To prevent this, I put vitriol in the ink.' Rashi explains that (the extension) will not be totally obliterated. If we are concerned lest a fly extend letters, there is still concern! It seems that the Rema (EH 125:15) is concerned for this! He says that if a fly extended the ink in a Get, we do not erase it. The Rambam did not say that Kefel is less because the bearer has the lower hand. Rather, he shows that Kefel and Sefel are different, and in every case we follow the bottom, whether it is a leniency or stringency. The Tur says that the bearer has the lower hand to explain why we are concerned for a fly, which is a more remote possibility, and we do not attribute the discrepancy to a retraction. If the bottom says Kefel, in any case he gets only Kefel. Do not ask why here we do not say (that we follow the smaller amount) like we say about other contradictory expressions (218:14, 312:15). The Nimukei Yosef (Bava Metzia 59b) explained that this is only when they are next to each other, e.g. 'Istira, 100 Ma'im.'

Gra (24): According to the Rambam, it is always a Safek (for a fly can also lengthen). If the bearer seized, we do not take from him, even though it is a Sefek Sefekah; see Rema (390:2) (some say that seizure does not help when there is a Safek about the Halachah).

Birkas Eliyahu (citing Be'er Eliyahu): Two Sefekos favor the borrower. Perhaps also above it said Kefel, and a fly made it Sefel. Or, perhaps nothing was changed, and we follow the bottom. Even so, if the lender seized he keeps it, for perhaps below it said Kefel.

Note: This is called a Sefek Sefekah, even though it matters only what was written below, whether or not the top was changed!

Gra (ibid.): This is also relevant to a receipt (the lender cannot prove that it is for the smaller amount), like the Rema says in Sa'if 8. Also, in Sa'if 5 we say that when we can resolve the discrepancy, we do so. According to the Rambam (we can resolve either way, i.e. both should say Kefel or both Sefel), so the bearer has the lower hand.

Shulchan Aruch (8): In all these cases that we say that the bearer has the lower hand. If he seized Metaltelim, we do not take them from him.

Beis Yosef (DH u'Mah she'Chosav v'Iy): The Rif says so (Bava Metzia 59b). The Ramban explains that this is when the borrower willingly gave the larger amount to the bearer. Hagahos Maimoniyos (Hilchos Malveh 27:300) explains that the bearer has the lower hand due to ha'Motzi mi'Chavero Alav ha'Re'ayah. Now that the bearer seized, the borrower is the Motzi. The Magid Mishneh (27:16) says that this is even if he seized in front of witnesses. However, if the document says 'Dinarim', and witnesses saw him seize more than two, he must return the excess. The Tur discusses such a document after discussing seizure, to show that there seizure does not help. Seizure does not apply to land.

Shach (15): The SMA (23) and Poskim say that even if he seized without Reshus (permission), he keeps it. The Rosh (Bava Basra 1:13,8:30) and many others connote like this, unlike the Ramban brought in the Beis Yosef. I say that they do not argue. The Poskim discuss a bearer who has a Vadai claim, and the Ramban discusses when he has a Safek claim. The Rosh (Bechoros 1:15) cites the Ramban, for they do not argue.

Shach (16): Seizure does not help for land, even for attached produce, even if the bearer is Vadai (unless he has a Migo), for land is in its owner's Chazakah.

Rema: All the more so, regarding a receipt we say that the bearer has the upper hand, for he is Muchzak. This is unlike those who disagree and say that even regarding a receipt, he has the lower hand.