Demai, Chapter 3, Mishnah 3. We continue with a principle we have already learned: a person who has taken possession of certain produce must be careful to separate tithes from it before it leaves his hands.
"HaMotzei peiros baderech":
"HaMotzei peiros baderech" - one who finds produce on the road. The case is produce that has already become obligated in tithes, since it is evident that it has been processed.
"Venetalan le'ochlan venimlach lehatzni'a" - he picked it up in order to eat it, and afterwards changed his mind and decided to store it away.
"Lo yatzni'a ad sheye'aser" - he may not store it away until he separates tithes. The reason: once he picked it up in order to eat it he became its owner, and now that he is storing it away there is a concern that another person will find it and eat it without separating tithes.
"Im mitechilah netalan shelo yovdu - patur" - if from the outset he picked it up only so that it would not be lost, and not in order to acquire it for himself, he is exempt, since he never acquired actual ownership of it.
"Kol davar she'ein adam rashai lemochro demai":
We have already noted the difference between a coarse measure and a fine measure: one who sells in small quantities must separate from demai, whereas one who sells in large quantities need not separate, and may leave the separation to the buyer.
From here the Mishnah rules: "Kol davar she'ein adam rashai lemochro demai - lo yishlach lachaveiro demai" - anything that a person may not sell as demai, he may also not send to his fellow as demai, even as a gift. This refers to a case in which a small quantity is being sent.
The view of Rabbi Yosei: "Rabbi Yosei matir bevadai, uvilvad sheyodia" - Rabbi Yosei permits sending certain tevel, provided that he informs his fellow that tithes have not been separated from it; and since he has informed him, the recipient will separate the tithes himself.
Regarding demai: Even Rabbi Yosei agrees that one may not send it to him, because since people are generally lenient with demai, there is a concern that he too will be lenient and will forget to separate tithes from it before eating it.
In summary: in this Mishnah we learned two laws. The first: one who finds produce that is obligated in tithes and picked it up in order to eat it, and then changed his mind and decided to store it away, may not store it away until he tithes, since he became its owner and there is a concern that another person will find it and eat it without separating; but if from the outset he picked it up only so that it would not be lost, he is exempt, since he never acquired it. The second: anything that a person may not sell as demai, he may also not send to his fellow as demai; and Rabbi Yosei permits it with certain tevel provided that he informs the recipient, but agrees that demai may not be sent, out of concern that the recipient will be lenient and forget to separate.