Yerushalmi Terumot 4:1 ירושלמי תרומות ד׳:א׳

MISHNAH: If somebody separates parts of heave or tithes, he takes from this its own heave or tithes but not for another place¹R. Simson explains: If somebody desires to give the full amount of heave (Mishnah 3) but at the moment takes only a smaller amount, or if he does not take the full 10% as tithes, then what he took is heave or tithes but the remainder is profane food and ṭevel mixed together and he may take the rest of his obligation from the same heap since, in this case, we say that what he takes out is ṭevel and not profane. {For heave he must have the intention to give more since there is no biblical minimum for heave.} But for another heap we do not allow him to take heave or tithes from what is partially profane. R. Meїr’s position is that we accept that heave taken in any permissible way retroactively turns its material into ṭevel, so that in any case only correct heave or tithes were taken (cf. Demay Chapter 5, Notes 45,63.).
Maimonides explains the Mishnah as stating that partial heave or tithes possibly remain ṭevel and therefore one must give heave or tithes from the separate produce. It cannot be returned to the original heap because possibly it is heave. R. Meїr considers it certain ṭevel. R. Abraham ben David (Ma‘aser 1:15) declares “I have no idea where he or his teacher could have picked up such an idea,” but the correct explanation is that given by R. Simson.. Rebbi Meїr says, he may even take it for another place.

HALAKHAH: “If somebody separates parts of heave or tithes,” etc. Our Mishnah [is said] in case he separated and it is his intention to separate more. Rebbi Samuel in the name of Rebbi Zeїra, our Mishnah [is said] if he did not say anything. Rebbi Mana said before Rebbi Yudan: Do they disagree? He said to him, if he did not say anything, it is as if it were his intention to separate more²The only case where an amount of heave smaller than the rabbinic minimum is accepted as full heave if the person giving heave says so explicitly..

What is the difference between taking from itself for itself and taking from itself for another place? When it is from itself for itself, what comes into his hand is³Retroactively, it turned out to be heave. But if used for another heap, there is no retroactivity and heave and ṭevel are indistinguishable. all ṭevel. If he separates from it for another place, both together come into his hand. That is difficult⁴Clause missing in Rome ms., but quoted by R. Simson.: If he took [produce] with the intention of taking from itself for itself, what comes into his hand is all ṭevel. If he changed his mind to use it for another place, both together come into his hand! If he took [produce] with the intention to use for another place, both together come into his hand. If he changed his mind to take from itself for itself, all that came into his hand is ṭevel! If he gave too little, all that came into his hand is ṭevel⁵This is the case of our Mishnah. The clause is missing in the Leyden ms.. If he added, both together came into his hand⁶If we speak of heave, what he separated was more than he intended. If we speak of tithe, his produce is in order but his tithe is not, as stated in Demay Chapter 5, Note 40..

Also if he is in error it is so. If he thought that two se’ot were due but he owed only one, Rebbi Immi in the name of Rebbi Simeon ben Laqish: That [extra] seah which he separated he gives as heave for another place. But did we not state: “but not for another place”? Explain it if he increased the heave⁷The Mishnah is irrelevant here since it deals with the case that too little heave was given. It is permissible to give too much heave since its amount is not determined in biblical law, in contrast to tithes. Since the extra seah was declared as heave, it must remain in the sanctity of heave.. It is acceptable if he increased the heave, but what about tithes? Rebbi Simeon ben Laqish did not state about tithes. But the reason of Rebbi Simeon ben Laqish must be that, since we say that all the ṭevel is now in his hands, what is the difference between taking from it its own heave or that for another place⁸If the reason given above, that we declare that all produce in his hand the second time around was genuine ṭevel, then this ṭevel should be usable for heave in all possible ways. He will restrict the use of the second batch only for freeing its own produce for tithes and heave of the tithe.?

That is⁹If the heave given was more than 50% of what was due, one follows R. Simeon ben Laqish. If less than 50% was given, one follows R. Eliezer ben Jacob in this paragraph. The Mishnah therefore is valid only in case exactly 50% were given., if most of the heap was put in order. If most of the heap was not put in order, there is disagreement between Ḥizqiah and Rebbi Joḥanan. As Rebbi Simeon ben Laqish said in the name of Ḥizqiah, ṭevel becomes voided by plurality¹⁰He disagrees with the generally accepted statement that by rabbinic decree, the prohibition of anything that can be put in order is not voided if it becomes an indistinguishable part of other produce or food; cf. Ševi‘it 6:3, Notes 117–121. It is agreed that in biblical law, the prohibition of any food becomes void by a plurality of permitted matter. Cf. also Halakhah 8, Note 71., but Rebbi Joḥanan said, ṭevel does not become voided by plurality. Since it was his intention to give, each single grain of wheat was labelled at its place¹¹As noted before, if it was the farmer’s intention to put in order only part of the heap, then the remainder is ṭevel and no one knows which grains are profane and which ṭevel.. Some want to explain following Rebbi Eliezer ben Jacob, as Rebbi Eliezer ben Jacob stated, that he cannot separate either for itself or for another place¹²If humans cannot distinguish between profane and ṭevel, humans cannot use the remainder of the heap for heave or tithes.. This parallels the following¹³The following text is from Chapter 2, Notes 26–28.: If there were before him two heaps and from each of them he took part of heave or tithes, may he take heave or tithe from one for the other? The students of the elder Rebbi Ḥiyya asked the elder Rebbi Ḥiyya and he said to them (Eccl. 4:5): “The fool folds his hands and eats his own flesh.” Rebbi Eleazar in the name of the elder Rebbi Ḥiyya: He may not give heave or tithe from one for the other.