כאשר יוכלון שאת. פירש הרמב"ן ז"ל יותר מן המגיע להם בכסף אשר הביאו לו. כאשר יוכלון שאת, “as much as they were able to carry.” According to Nachmanides this means that Joseph provided them with far more grain that they were entitled to for the amount of money they had brought with them.
ושים כסף איש בפי אמתחתו. כסף שני זה לדעתם, שאם עשה זה כפעם הראשונה שלא לדעתם היה להם התנצלות בגביע שנעשה בו כאשר נעשה בכסף, אבל היה זה לדעתם וידעו בכסף כאשר ידעו במשא כי הכירו כי נתן להם כאשר יוכלון שאת. ואם היה שלא לדעתם אולי טען עליהם כי היה הכסף גם בפעם הזאת מטמון ולא יתכן כן בגביע, ומי יוכל לדון עם שתקיף ממנו.
ושים כסף איש בפי אמתחתו, “and place each one’s money at the top of his feeding bag.” This time their money was replaced with their knowledge, as opposed to the first time. Had Joseph not advised the brothers that he was returning their money (at least the money they brought as substitution) they would have a valid excuse once the goblet would be discovered in Binyamin’s sack. Now that Joseph had proven that he dealt with the brothers in an above-board manner, they would not be able to claim that he had once before deceived them by planting something in their luggage. They were also aware that Joseph had loaded their beasts to the utmost capacity. Joseph might have argued that even this time the money which he put in their sacks was a gift from G’d, an argument that could not be used as applying to his goblet.
If we were to assume that now too the money the brothers found in their sacks had been placed there without their knowledge, he might have argued that whereas the money was again a treasure their G’d had granted them, the same could not apply to his personal goblet. They would not be able to argue (successfully) with someone stronger than they.
ודע כי בעבור היות השוברים רבים מאד בכל ארץ מצרים ומהומות רבות בתוכה היו הבאים נותנים שקיהם וכספיהם למשביר והוא מודד להם כפי הכסף הנמצא והם לוקחים הנתון להם באשר דבר מלך שלטון, ועוד כי באמונה הוא עושה, ועל כן לקחו פעם ראשונה גם בשניה שקיהם סגורים ולא ידעו מה שבתוכם. Remember that Egypt was a country in which there occurred many disturbances (compare Amos 3,9). In order to avoid becoming victims of muggers etc., the travelers who came to Egypt to buy grain entrusted their beasts, their sacks as well as their money, to the officials who would measure out the grain for their rations. The official would measure out grain for them in accordance with the amount of money they had deposited with him. The buyers would accept what was given to them without double-checking and thereby displaying distrust in the Egyptian government (based on Kohelet 8,4). The brothers therefore had good reason not to appear suspicious and to double-check what Joseph’s officials had done when filling their sacks.