Insurance and Unsa d'lo Schiach

... It is related: There was a certain man who sold land to another, and he accepted upon himself the responsibility for any unavoidable accident that may happen to the land. In such a case he would reimburse the buyer for the damage. In the end they diverted a river into it, meaning the government decided to make a new canal through the land that he sold. The buyer came before Ravina to lodge a claim. Ravina said to the seller: Go pacify him, i.e., reimburse him, as you accepted upon yourself responsibility for any unavoidable accident that might happen. Rav Aḥa bar Taḥalifa disagreed and said to Ravina: It is an uncommon, unavoidable accident, and the condition of the sale should not apply in such a case. The matter was circulated, as this ruling was never finalized, and it came before Rava. He said to them: It is an uncommon, unavoidable accident, and the seller should not have to pay.

...It is related that Rav Pappa and Rav Huna, son of Rav Yehoshua, purchased sesame on the bank of the Malka River. They hired sailors to cross them to the other side of the river, and the sailors accepted upon themselves responsibility for any unavoidable accident that might occur. In the end the Malka River was dammed so that the merchandise could not be transported by river. The two Sages said to them: Hire donkeys and release them to us in order to transport the sesame, as you accepted upon yourself responsibility for any unavoidable accident that might arise. The two Sages came to court before Rava and he said to them: You white geese [kakei ḥivarei], referring to their long, white beards, who strip men of their cloaks. You are acting unfairly with the sailors. It is an uncommon, unavoidable accident for the Malka River to be dammed, and the sailors did not accept responsibility for this case.

This appears to pertain to common price fluctuations, but an uncommon rare increase in cost was implicitly not agreed to during the acceptance of responsibility, see Choshen Mishpat 225

If he says to her, "Behold this is your get if I don't come [back] within 30 days," or he says, "On condition that I don't come [back] within 30 days," and he is on the way to come back within 30 days but he gets sick or he is prevented because of a river, and he only comes after 30 days, the bill of divorce takes effect, even if he stands and protests, "I was an oneis [the events were not in his control]!" For there is no oneis in regard to divorce. And [this is so] even though his intent was openly known that he did not want to divorce, since he did not stipulate "except for the case if I become an oneis." But an oneis that is very uncommon, such as being attacked by a lion or being bitten by a snake or a house fell on him, he never intended for that to make a condition on, and the bill of divorce is void [and if he dies] she is bound to the yibbum [levirate marriage]. Rem"a: And if he becomes a captive, that is a common oneis, and the bill of divorce is not void because he did not stipulate [the exception] (Mordechai Perek Mi Sheachzo).

Anyone who sells land or a slave or other objects is obligated in a responsibility for the sold item. How so? If a third party seized the asset from the purchaser due to debts of the seller, the purchases can claim a full refund from the seller. This is the law for every sale even without specifying any such thing, including a plain sale. Even if the sale was done with a legal contract and the contract neglected to mention the liability of the seller in these matter nevertheless the responsibility is present, for the absence of such a clause is considered an error on the part of the scribe.

These laws only apply when the third party seized the asset under the auspices of a Jewish court of law (Beit Din). This would include if the seller had initially stolen the land. If, however, a gentile was the cause for the asset seizure then no refund can be claimed, even if the gentile documents that the seller originally stole the asset from him. This is considered Ones a rare/unexpected setback, and no responsibility to refund is present.

However, if the contract stipulated that the seller accepts responsibility for anything bad (Ones) that might happen to the asset, then even if the asset is stolen by bandits the seller must compensate the purchaser.

If, however, a river is stopped causing the land to be flooded or a monsoon caim and ruined it the seller is not obligated to refund, because RARE ACCIDENTS are implicitly excluded in the accepting of responsibility for all accidents.

And this is the law for all contracts pertaining to monetary matters, we (implicitly, legally) exclude from any explicit conditions anything except that which is reasonably anticipated during the moment of stipulation.

A vow of Ones such as one who swears to eat at his friends home but became ill, or his son became ill, or he was blocked by a river, these are all accidents Ones and do not require formal vow annulment.

[Commentary discusses what the relative infrequency must be in order to qualify as implicitly excluded during the moment of the vow.]

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