פירוש על בראשית 42:27

ויפתח האחד literally, AND THE ONE OPENED HIS SACK — This was Levi who remained alone (one) being without Simeon his companion (cf Targum Jonathan).

AND AS ONE OF THEM OPENED HIS SACK. One of them opened his sack in the inn to give therefrom some fodder to his ass, while the others did not open their sacks until they were with their father, just as it says, And it came to pass as they emptied their sacks,¹⁵⁵Verse 35 here. for perhaps the others took straw for their asses, lest they consume their entire loads on the way. But the one who opened the sack on the way had a weak ass, which required fodder, and he thus found the money in the mouth of his bag (‘amtachto’).
Now Rashi writes that amtachath is the sack, but Onkelos translated it as “load.” It appears from Onkelos’ opinion that each one in order to equalize his load, had large sacks and small sacks, and the total load of each one is called amtachath. Thus it happened that one of them found his money at the mouth of the particular sack he opened, while it did not happen to the others until they emptied all their sacks.
It seems plausible to me that amtachath is a large sack containing two sides, known in the language of the Talmud as matrata,¹⁵⁶Kethuboth 110 a: hafuchi matrata lamah li, meaning that if a person is carrying two leather sacks of equal weight on his right and left shoulders, why should he change one sack for the other? (See Rashi there.) and the money of each one was put at the mouth of one of the sides. Now it so happened that one of them opened the side where the money lay, but it did not happen to the others. This kind of sack is called amtachath because it stretches (yimtach) at the sides.

ויפתח האחד, one of them. According to a homiletic comment quoted by Rashi, the definitive article at the beginning of the word האחד is a hint that this was Levi, who, through his buddy Shimon having been detained by Joseph, was now “the one,” i.e. left alone without his closest companion.

ויפתח האחד את שקו, “the one opened his sack;” Noachmanides writes that the emphasis on האחד, “the one,” means that the other brothers did not bother, at that stage, to open their sacks and to examine their contents. They waited till they had arrived back at their father’s house. Perhaps the reason why this one brother opened his sack (the one containing fodder) may have been that his donkey was relatively weak and needed something more than straw to keep up its strength. Onkelos who translated the word אמתחת as טוענא, a carrying bag, wants to tell us that the most commonly used container to carry and transport loads was called שק, sack, whereas containers containing personal effects, such as are carried in briefcases nowadays, were called אמתחת, travel bag. Well to do travelers frequently had several of the latter. Sometimes these travel bags were also used to balance the loads carried in sacks. It was therefore surprising to find one’s money in a sack intended to carry grain, rather than in one of the travel bags. In our example the אמתחת appears to have been carried inside the sack of grain, at the op of it, as a security precaution, maybe. The very term אמתחת may imply that this bag had compartments, and that different objects would be enclosed in different compartments. A simpler explanation is that the brother who opened his sack did so in order to give fodder to all their donkeys. My father, blessed be his memory, the רא'ש, says that the brother referred to as “the one,” was Levi, who though normally inseparable from Shimon, was now “alone,” seeing Shimon had been detained by Joseph in Egypt. Seeing that Levi was leading two donkeys, his own and that of his brother Shimon, as he already had occasion to dip more deeply into the sack of Shimon, he found the money at the bottom. The other brothers, each of whom had only one donkey to feed, had not yet had to dip so deeply into their sacks.

This was Leivi because he was left alone... [Rashi knows it was Leivi] because otherwise, why does it say, “The one”?

Das Verhältnis von שק zu אמתחת ist dunkel. שק, von שקק, wahrscheinlich gleichbedeutend mit נסק, wovon ק וגו׳oאם אֶ hinaufsteigen, ein Tragmittel, von der Wurzel des Hinaufsteigens gebildet, wie סַל Korb von אמתחת .סלל von מתח ausdehnen, scheint einen größeren, dehnbaren Behälter zu bedeuten, in welchem mehrere Säcke und Bündel zusammen bewahrt werden. Es ist ja auch nicht wahrscheinlich, dass das Geld in den Kornsack gelegt worden sei, in welchem es ja leicht unter das Getreide gekommen wäre, ohne sofort sichtbar zu werden.

במלון means the place where they stayed over night — THE INN.

בפי אמתחתו, Joseph had instructed that the money of one of them should be not just placed back in his sack, but should be placed near the top so that he would find it immediately he opened the sack. The money of the other brothers had been placed somewhere in the middle section of their respective containers, or even at the very bottom. If the money of all of them had been placed near the top of their bags they would see it as soon as they started giving fodder to their beasts, and they would turn around to Egypt pointing out that someone had made a mistake. They would be anxious to clear themselves of the danger of being accused of an additional crime, of being thieves. Joseph had therefore taken precautions that only one of them should find his money before they would get home. He had arranged matters in a way to cause them maximum worry.

At the place they stayed overnight. [Rashi is saying:] Do not think that since it is written בַמלון [rather than בְמלון] it means the place set for all wayfarers to stay. For if so Scripture should have written, “They came to the מלון,” and only afterward say, “The one opened his sack...at the מלון.”

אמתחתו is the sack (שק) just mentioned.

It is the sack. Rashi says, “It is the sack,” rather than simply saying, “Sack,” because he is answering the question: At the beginning of the verse it is written, “One of them opened his sack.” And afterwards it is written, “For behold it was in the opening of his bag.” Does this not imply it was not the [abovementioned] sack? Thus Rashi explains, “It is the sack.” In other words, the bag mentioned here is the same sack mentioned before.