Why did Yaakov again request that they go to Egypt to buy grain, ignoring their original refusal?
Seforno: Because he thought that they wanted to take Binyamin down to Egypt to get rid of him, like they did to Yosef. 1
Refer to 42:36:1:1*.
If they finished the food, what would they eat until the brothers went again and returned?
Ohr ha'Chayim #1: "Kilu" means that there remained only enough until they would go [to Egypt] and return. It is called "Kilu" because they need to bring more.
Ohr ha'Chayim #2: They finished "the grain that they brought from Egypt." They still had grain that Yaakov prepared for the years of famine (Ta'anis 10b). 1
The Gemara says only that [the first time] they were satiated, and Yaakov told his sons to go to buy merely to avoid envy. If this answer holds that they had more than what is needed until they can go to buy more and return, would Yaakov agree to endanger Binyamin?! (PF)
Why did he tell them to buy "a little" food?
Malbim: If you cannot bring much, at least you can bring a little, enough to stay alive.
Ha'amek Davar - They will accustom themselves to eat a little grain, and food that they despise. It is normal in years of famine to slowly get used to eating foods that one was not used to until now.
QUESTIONS ON RASHI
Rashi writes: "'When they finished consuming [the food]' - Yehudah had said to them, 'Wait with Grandfather, until the bread in the house is finished.'" How do we know that Yehudah was waiting specifically for this time?
Gur Aryeh: Yehudah was willing to forfeit his Olam ha'Ba if he failed to bring Binyamin home (43:9); so why didn't he say so immediately, right after Yaakov dismissed Reuven's offer (42:38)? This must have been Yehudah's strategy - to wait until the lack of food forced them to return to Egypt.
Rashi writes: "Wait... until the bread in the house is finished." Why does Rashi tell us this here?
Gur Aryeh: The Pasuk's expression, "when they finished consuming the food," makes it sound like this is what happened; not that anyone had planned it that way. Rashi must explain that this was Yehudah's strategy [ever since they returned].
