The Gemara discusses whether a person can make something Asur to others ever after the object leaves the Reshus of the Noder. It proves that this can be done from the Mishnah in Bava Kama (in which a person prohibits his sons from using his possessions even after death).
Then the Gemara says that the Amora'im argue whether a person prohibits objects on himself even after he sells them, when he uses the word "Nechasam Elu", and cites proof that one does prohibit them.
But isn't it obvious that a person can prohibit things on himself for after he sells them? He can even prohibit them on himself while they belong to others, certainly when there are his he can prohibit them? What, then, is the question regarding the second part of the Gemara?
Tuvya Marcus, Jerusalem, Israel
Hello there and thanks for your question. The point you raise is correct, however I do not think that this is the Pshat in the Gemara. R. Yochanan and Reish Lakish are arguing in the case where one prohibits his item on others. At first we thought that the issue was "Does this have any effect after it leaves his posession?". The Mishnah in Bava Kama proves clearly that it does have effect. Then we explain that the argument is whether the language (Nichasim Eilu vs. Nechsai) makes a difference. We then quote the Mishnah which proves that the two languages have different meanings. It is true that the Mishnah is dealing with a case where a person forbids it upon himself (not upon others, as is the case we're dealing with), but the Mishnah clearly shows that the terminology makes a difference, and that if a person uses the term "Nechasim Eilu" it means even after it leaves his possession. Thus in our case this cannot be the point of contention between Rav Yochanan and Reish Lakish.
I hope this clears the matter. If not, please feel free to inquire again.
All the best.