Though Jacob's sons were all married, and had families of their own, yet, it should seem, they were still incorporated in one society, under the conduct and presidency of their father Jacob. We have here,
I. The orders he gave them to go and buy corn in Egypt, Gen 42:1, Gen 42:2. Observe, 1. The famine was grievous in the land of Canaan. It is observable that all the three patriarches, to whom Canaan was the land of promise, met with famine in that land, which was not only to try their faith, whether they could trust God though he should slay them, though he should starve them, but to teach them to seek the better country, that is, the heavenly, Heb 11:14-16. We have need of something to wean us from this world, and make us long for a better. 2. Still, when there was famine in Canaan, there was corn in Egypt. Thus Providence orders it, that one place should be a succour and supply to another; for we are all brethren. The Egyptians, the seed of accursed Ham, have plenty, when God's blessed Israel want: Thus God, in dispensing common favours, often crosses hands. Yet observe, The plenty Egypt now had was owing, under God, to Joseph's prudence and care: if his brethren had not sold him into Egypt, but respected him according to his merits, who knows but he might have done the same thing for Jacob's family which now he had done for Pharaoh, and the Egyptians might then have come to them to buy corn? but those who drive away from among them wise and good men know not what they do. 3. Jacob saw that there was corn in Egypt; he saw the corn that his neighbours had bought there and brought home. It is a spur to exertion to see where supplies are to be had, and to see others supplied. Shall others get food for their souls, and shall we starve while it is to be had? 4. He reproved his sons for delaying to provide corn for their families. Why do you look one upon another? Note, When we are in trouble and want, it is folly for us to stand looking upon one another, that is, to stand desponding and despairing, as if there were no hope, no help, - to stand disputing either which shall have the honour of going first or which shall have the safety of coming last, - to stand deliberating and debating what we shall do, and doing nothing, - to stand dreaming under a spirit of slumber, as if we had nothing to do, and to stand delaying, as if we had time at command. Let it never be said, "We left that to be done tomorrow which we could a well have done today." 5. He quickened them to go to Egypt: Get you down thither. Masters of families must not only pray for daily bread for their families, and food convenient, but must lay out themselves with care and industry to provide it.
II. Their obedience to these orders, Gen 42:3. They went down to buy corn; they did not send their servants, but very prudently went themselves, to lay out their own money. Let none think themselves too great nor too good to take pains. Masters of families should see with their own eyes, and take heed of leaving too much to servants. Only Benjamin went not with them, for he was his father's darling. To Egypt they came, among others, and, having a considerable cargo of corn to buy, they were brought before Joseph himself, who probably expected they would come; and, according to the laws of courtesy, they bowed down themselves before him, Gen 42:6. Now their empty sheaves did obeisance to his full one. Compare this with Isa 60:14 and Rev 3:9.

Jacob saw that there was corn - That is, Jacob heard from the report of others that there was plenty in Egypt. The operations of one sense, in Hebrew, are often put for those of another. Before agriculture was properly known and practiced, famines were frequent; Canaan seems to have been peculiarly vexed by them. There was one in this land in the time of Abraham, Gen 12:10; another in the days of Isaac, Gen 26:1; and now a third in the time of Jacob. To this St. Stephen alludes, Act 7:11 : there was great affliction, and our fathers found no sustenance.

And Joseph's ten brethren went down to buy corn in Egypt. They obeyed their father's orders, and immediately set out for Egypt; "ten" of them went down in a body together, all but Benjamin, so that it is easily reckoned who they were, and they are called not Jacob's sons, as they were; but Joseph's brethren, whom they had sold into Egypt, and to whom now they were going, though they knew it not, to buy corn of him in their necessity, and to whom they would be obliged to yield obeisance, as they did.
And Joseph's ten brethren went down to buy corn in Egypt. They obeyed their father's orders, and immediately set out for Egypt; "ten" of them went down in a body together, all but Benjamin, so that it is easily reckoned who they were, and they are called not Jacob's sons, as they were; but Joseph's brethren, whom they had sold into Egypt, and to whom now they were going, though they knew it not, to buy corn of him in their necessity, and to whom they would be obliged to yield obeisance, as they did.
Genesis 42:4

gen 42:4
gen 42:4
gen 42:4But Benjamin, Joseph's brother, Jacob sent not with his brethren,.... Benjamin is called Joseph's brother, because he was so both by father and mother's side, as the rest were not; him Jacob kept with him, being the youngest and his darling, the only son he had with him of his beloved wife Rachel; and was very probably the more beloved by him since he had been bereft of Joseph; and it was not only to keep him company that he retained him at home, but for the reason following:

for he said, lest peradventure mischief befall him; as had to Joseph his brother, as he imagined; either that the journey would be too much for him, being young, or lest he should be seized with sickness on the road, or rather with death, as Aben Ezra interprets it according to the Targums of Onkelos and Jonathan.