פּירוש אויף בראשית 42:3

וירדו אחי יוסף AND JOSEPH S BRETHREN WENT DOWN — It does not call them “the sons of Jacob” (as in 5:5), thus suggesting that they regretted having sold him and that they had made up their mind to behave towards him in a brotherly manner and to redeem him at whatever price people might fix for them to pay (Midrash Tanchuma, Miketz 8).

וירדו אחי יוסף. The reason why the Torah describes them all of a sudden as “Joseph’s brothers” instead of as Yaakov’s sons, is that they went down to Egypt because of what had happened with Joseph so many years ago. The time had come for Joseph’s dream to be realised, and the Torah wants to alert the reader to this. In Bereshit Rabbah 91,2 the question is raised why there is a dividing tone sign, etnachta, under the word עשרה, as if the verse ended there. The answer given is that nine of the brothers only were concerned with finding Joseph and being good brothers, whereas the tenth, Shimon, joined them only in order to buy grain. [the basis of the Midrash is the number “ten” being mentioned. We all knew that only ten brothers went to Egypt, Yaakov not allowing Binyamin to join them. Hence, the Midrash reads additional meaning into the word “ten,” as well as into the tone sign under that word. Ed.]

וירדו אחי יוסף עשרה, the official selling grain in Egypt did not sell to more than one family per buyer. The reason for this restriction was intended to ensure that the buyers would not resell some or all of what they had bought, thus using what Joseph had stored as a source of enriching themselves.

עשרה TEN — What is the mention of this number intended to tell us? Is it not written (Genesis 42:4) “but Benjamin, Joseph’s brother did he not send” (and we therefore know that only ten brothers went to Egypt)? But it means to suggest that so far as their feeling of brotherhood towards Joseph was concerned they were divided into ten, because the love and hatred that all of them bore him were not alike, where as in regard to buying corn they were at one and united (Genesis Rabbah 91:2).