Bava Metzia, Chapter 1, Mishnah 7. The Mishnah before us continues to deal with found documents and the question of the obligation to return them, but this time it involves documents that are not promissory notes - they are not financial obligations - and nevertheless, it states regarding them that one should not return them, even though it is seemingly clear who the recipient is and to whom they belong. The reason is common to all the cases: it is possible that the documents were written and never delivered. Documents of this type are written in advance, and there is no certainty that it was indeed appropriate to deliver them to the recipient. Since their delivery has weighty consequences, it is possible that there was never an intention to deliver them.
"Matza gitei nashim veshichrurei avadim":
"Gitei nashim" - One who finds a woman's get, a bill of divorce. The Mishnah uses the plural form, but there is no difference between one or multiple, and the simple assumption is that it refers to one. He should not return it, lest the husband instructed that the get be written and ultimately changed his mind and never delivered it to her.
"Veshichrurei avadim" - A bill of manumission for a slave. The owner of a Canaanite slave or Canaanite maidservant frees them in a process similar to divorce: they are given a document very similar to a get, in which it is written that they are going free and are under their own authority. Here too, a person might go to a scribe and ask that the document be written in advance, and there is no knowing whether he indeed intended to execute it and deliver it to the slave. Perhaps he reconsidered, and the document was lost. Delivering it to the slave would unlawfully set him free.
"Deyatiki":
To transfer ownership of an object, an act of kinyan is usually required - a formal action that transfers ownership. If one wishes to give an expensive watch to his friend, the friend must lift it in order to acquire it (and it is even possible to lift it on his behalf to acquire it for him). However, a mere statement, "I hereby give my watch to my friend," is completely ineffective, and the watch remains in the possession of its owner. And if he dies afterward, his heirs and children will acquire it, and not the friend.
However, in the case of a shechiv mera - a person on his deathbed - the Sages enacted a special decree. A person arranging his financial affairs before his death is in great anxiety: he remembers that he promised his good friend his watch and did not fulfill it, and now he will die, the item will pass to his children and his name will be tarnished. The Sages were concerned that the stress and anguish of not arranging his affairs would hasten his death, and therefore they established that for a shechiv mera, an oral declaration is sufficient, and his speech alone carries the same weight as a complete, legal act of kinyan that transfers ownership properly.
It turns out, then, that if the shechiv mera said: "It is my desire that my good friend receive my watch as I promised him," his words are binding, and after his death, the watch will be given to the friend and will not pass to the heirs. This is a Rabbinic law.
It was accepted practice to put these instructions in writing, since without being written down they are liable to be forgotten and cause confusion. A deyatiki, therefore, is a written record of a shechiv mera's requests, regarding the distribution of certain assets while he is still alive: it is written in it that so-and-so is on his deathbed, and stated his desire to give his watch to his friend before his death. And nevertheless, we do not deliver it to the beneficiary, lest he forcefully take the watch from the children, whereas the document may not have had any validity in the first place - it is possible that the shechiv mera retracted, did not want this, and did not execute the matter.
"Umatanah":
The same applies to a regular gift document. There are ways to transfer ownership even when the recipient is not present, such as a kinyan sudar, and the document testifies: "I hereby transfer my watch" or my house, "to so-and-so as a gift." Such a document may be halachically binding when executed properly. And nevertheless, one who finds such a document should not deliver it to the recipients named in it, lest the giver changed his mind and ultimately decided not to give it, and did not deliver it, and did not intend to deliver it, and did not perform the actions required for its transfer. Delivering the document is therefore liable to be unlawful.
"Veshovar":
A shovar is a receipt. The standard practice, as explained in the previous Mishnah, is that a borrower who repays his debt receives the promissory note back from the lender and tears it up. This is similar to an uncashed check: the lender lends a hundred dollars and receives a check, stipulating that he will not deposit it provided the cash is returned to him, and when it is returned - he will return the undeposited check.
What is to be done when the borrower comes with the hundred dollars and asks for the promissory note, but the lender answers that he lost it? The borrower is still obligated to repay his debt, but if the promissory note remains with the lender, or if it is found in ten years' time, the lender could claim that the debt was never repaid and collect it a second time. Therefore, he must give a receipt - a proof of payment - to the borrower, stating that on such-and-such date, so-and-so returned the hundred dollars that he owed from that loan. Thus, if the lender produces the note in the future and tries to collect, the borrower will say: "I paid you, and here is the proof - I have a receipt in my possession."
Seemingly, one might think that someone who finds a receipt should return it to the borrower, since for whom was the receipt written by the lender if not for him? However, here too, it is possible that the lender had it prepared in advance by the scribe so that it would be ready in his pocket for the time when his debt is repaid; but ultimately, the debt was not repaid, the receipt was never given to the borrower, and it was subsequently lost. If it is handed over to the borrower now, he will be unjustly exempted from payment.
In all these cases - bills of divorce for women, documents of emancipation for slaves, wills, gift documents, and receipts - "harei zeh lo yachazir" - the finder should not return the document to the person to whom it seemingly belongs. The reason for this is explained in the Mishnah: "sha'ani omer kesuvim hayu venimlach aleihem shelo litnam" - it is possible that they were written properly, but afterward the writer changed his mind and never actually delivered the document, and giving it to the recipient would constitute an injustice.
This is the practical halachah. It goes without saying that if the writer himself says that the document should be given to the person for whom it was written, and he permits or instructs this to be done, the finder must give it to the recipient - to the slave, to the recipient of the gift, and the like.
However, when it comes to bills of divorce, the matter is more complex, because a woman's get must be written specifically for her sake, with absolute exactness: by this particular husband, for this particular wife, and for the sake of this particular divorce. Therefore, the get should not be given to the woman as her bill of divorce unless it is known with certainty that it was written originally for this specific woman, by this specific man, and for the sake of that very divorce.