פירוש על בבא קמא 15:14

Where it is possible to say [that the sale to] one of them preceded [the other sales]. It appears that Rashi understood that the words דאיכא למימר mean that an argument can be made that since one document was written and given before the other, we should consider the first purchaser as the first and his property should be collected last and we should not treat all of the purchasers equally even though all three transactions took place on one day. The Gemara’s conclusion is that since they are all written in one day the effective date of each of these documents is the end of that day. It doesn't really matter that one of them was written earlier than the others. They are in reality all effective at the same point in time, the end of the day on which they were written.
Tosafot seems to translate the words דאיכא למימר as ‘it can be said’. This implies that there is an element of doubt. It can be said that one was given before the other and it can be said that one was not given before the other. Tosafot finds this interpretation problematic. If we are speaking in terms of an actual time that the seller handed the documents to the buyers, then one definitely was given before the other. How can we entertain the possibility that one was not given before the other? (It is highly unlikely that the seller handed two documents to two people at precisely the exact same moment.) Tosafot explains that converse of “it can be said that one preceded the other” is not that “it can be said that the two documents were given simultaneously”, but rather, “that we are sure that one preceded the other”. This happens in Y’rusholayim where it was the custom to write not only the date but also the time of day that the document was written.
The reason that there is a doubt about which transaction occurred first in places other than Y’rusholayim is because we only write the hour of the day in Y’rusholayim. In Y’rusholayim there is no doubt. Since we write the hour of the transaction in the document we are sure that one document was given before the other.

It needs [to ask about a situation where] he sold to one [purchaser all of the fields] in one day. When the Gemara says: now if he sold three qualities to three people, they all take the place of the owner – and must pay each of the creditors according to the qualities that they purchased, i.e. the damages are paid from the finest, the creditor from the middle-quality and the k’suboh from the inferior fields, then certainly when there is only one purchaser he must pay each of the creditors with the quality that they deserve, it seems that there is no conceivable reason that would dictate that when there is a single purchaser he might be able to avoid paying the damages victim from his due – the finest. Tosafot holds that ultimately at the conclusion of the Gemara, this is not necessarily true.
In a few moments the Gemara introduces a new dynamic into the claims and counter-claims between the claimants and the purchaser of the debtor’s property. When the purchaser who is in possession of all three qualities purchased the finest quality last, it would seem that all the claimants can collect from the finest since that was the last one sold by the debtor. The Gemara says that the purchaser can argue as follows: If each of you is willing to accept the quality that is due to you, fine. If not, I will return the document of the poorest quality to the original owner and you will all have to collect from the poorest quality. With this claim the purchaser can avoid paying all of the debts with the finest property. Subsequently, the Gemara argues that he should not even pay the damages victim with the finest because he can threaten to return the inferior quality to the debtor/seller and compel him to accept the inferior quality.
Tosafot will now argue that when the sole purchaser purchased all of the fields on one day he too should also be able to avoid paying the damages victim with the finest quality, because he can threaten that he will return the document of sale of the inferior fields to the owner and they will be forced to accept the inferior quality. Thus he should be able to work out a compromise with the damages victim and pay him with middle-quality. It seems from the Gemara’s argument that precisely because one purchaser bought all of the fields, he can make this threat and is in a stronger position than if the three qualities were purchased by three individuals.
This contradicts the Gemara’s present position that when one person buys all of the fields, he must certainly pay according to qualities and not according to the order of the sales.
At this point the Gemara did not think of the explanation that a buyer may threaten the victim of damages who is seeking to be paid from the finest as follows: if you will be silent and accept the medium-quality that I will give you, fine, but if you insist on the finest, I will return the document of the sale of the poorest quality to the original owner and you will be forced to accept the poorest quality as payment of your damages. Eventually the Gemara presents this argument as a viable claim against the victim of damages who is seeking to collect from the finest property. If the Gemara had been aware of this argument, the Gemara could not have said that when all three fields are sold to one buyer, that buyer must certainly pay each of the claimants with the quality that he is due, for he could claim “if you will be silent etc.”
One might argue: Perhaps this claim is valid only when there are three separate documents for each of the three qualities, but if there is only one document for all three, the buyer cannot threaten to return the document of the poorest quality since they are all on one document?¹This is the underlying question that Tosafot addresses in his next statement. By Tosafot alluding to a problem when all three qualities of land were included in one document, we see that Tosafot has a different approach to the dynamics of the claim “if you will be silent etc.” Rashi and many Rishonim hold that this is a legal maneuver. The purchaser of the property can and will sell the poorest quality back to the seller/debtor. All the claims against him will be settled from the property in his possession which is the poorest. This follows the rule that one cannot collect a debt from sold properties when the debtor has unsold properties with which to pay the debt. By selling the poorest property back to the debtor, the purchaser can force the claimants to collect the debt from the poorest quality. All this is perfectly legal. According to this approach, even if all three properties were sold in one document the purchaser can re-sell the poorest to the debtor. The fact that they were originally sold in one document makes absolutely no difference. Since Tosafot does seem to have a problem with all three properties in one document, it is evident that Tosafot had a different view of the claim “if you will be silent”. It appears that this is not a legal sale of the poorest quality back to the seller/debtor. Since the Gemara does not use the term “I will sell the poorest to the debtor”, rather, “I will return the document to the debtor” Tosafot understands that we are not discussing a legal sale. It is a threat to suppress the document of the sale of the poorest so that it will appear that there never was a sale. If we work with this understanding we can see that there is a problem when all three qualities appear in one document. You cannot suppress only the portion of the document that deals with the poorest. Why would one use the threat of suppressing the document if he could simply sell the poorest quality back to the debtor/seller? Some say that selling the poorest back to the seller/debtor requires his cooperation. He must be willing to buy back the poorest quality. The Rosh assumes that he will be willing to do this in order to help the buyer. Tosafot holds that this assumption is not necessarily so. The seller/debtor may have reasons that it is not to his advantage to buy back the poorest quality. Tosafot therefore assumes that we are discussing a maneuver that does not require the cooperation of the seller/debtor which is the suppression of the document.
Tosafot explains:
For even when all three qualities were written in one document, the buyer can suppress that document and return the poorest quality to the seller as if he had never purchased it at all.²There are two major problems that the commentators ask about Tosafot’ explanation that the purchaser could suppress the document stating that all of Reuven’s property was sold to Shimon:
A) If he suppresses the document it will appear as if there was no sale at all and all of the debts will be paid according to the order of qualities. What does Shimon gain by suppressing the documentation of the sale? How can he use this threat to force the damages victim to accept the middle quality? If he follows through on his threat, the damages victim will collect his ‘finest’ from Reuven?
B) In conclusion the Gemara says that the reason the threat of returning the inferior quality is not viable is because the seller/debtor is no longer alive. According to Rashi’s explanation this makes perfect sense. Selling the inferior qualities to his heirs will not cause that the debtors must collect the inferior quality from the inheritors of the seller/debtor’s estate. When the property is sold to the debtor/seller he must pay from that property even though he re-purchased it, because he must pay with any property that he owns, whether he owned it at the time of the debt or it came into his possession at some later time, but the property that they purchase after their father’s death is not subject to collection for their father’s debts. For this reason, once Reuven dies the threat of returning the inferior quality is no longer effective. However, according to Tosafot understanding that we are discussing suppressing the document and creating the appearance that the inferior property was never sold, that can be done even after Reuven’s death. If we suppress the document of the sale, it will appear that the inferior lands were never sold and Reuven’s heirs inherited that property and they are subject to collection by Reuven’s creditors.
We find that the Gilyon in שיטה מקובצת answers the first question as follows: When Shimon suppresses the document that includes all qualities, he will re-write a new document stating that Reuven sold Shimon the finest and middle-qualities. In this way he protects the finest and middle-qualities from collection by retaining ownership of them and leaves the inferior quality in the possession of Reuven. The inferior qualities will be collected from Reuven because he has unsold property, which is always collected before the sold property that is in Shimon’s possession. This may also provide an answer to the second question. Since Reuven is no longer alive, a new document will have to be written between Shimon and Reuven’s heirs. This of course would mean that it would have the appearance that at the time of Reuven’s death these properties were still in his possession and thus subject to collection by his creditors. At this point nobody knows how many outstanding debts Reuven has and Shimon would not want the land he purchased while Reuven was still alive to be subject to such debts when in reality he had already purchased them and legally they are not subject to collection for those debts. Therefore, suppressing the original document and re-writing a new one with the heirs of Reuven is not a realistic threat.