What does Genesis 42:31 mean?
Ten sons of Jacob were sent into Egypt to buy grain (Genesis 42:1–5). Only nine have come back (Genesis 42:29–30). The governor of the nation accused them of being spies and kept one brother as collateral, until they return with their youngest brother, to prove their innocence (Genesis 42:18–19, 24).The defense they explain here is partly true. They are not spies. However, twenty years earlier, they jealously lied to their father after selling another brother, Joseph, into slavery (Genesis 37:28, 31–33). They've come to realize some of their predicament is divine punishment for their earlier crime (Genesis 42:21–22). That act caused their father intense sorrow (Genesis 37:34–35), and now they are forced to deliver another round of bad news.
Genesis 42:29–38 explains the results of Jacob's sons first trip to Egypt to buy food during a famine. There, the governor allowed them to leave only after keeping leaving Simeon as security, and demanding they return with Benjamin, the youngest, to prove their honesty. They also discovered—to their horror—that the money they paid the governor for grain was still in their bags. They do not know the governor is their own brother, Joseph (Genesis 37:28). However, Jacob refuses to risk losing yet another son and forbids the men to take Benjamin to Egypt.
Genesis 42 describes the moment Joseph sees his brothers for the first time since they sold him into slavery over 20 years earlier. They have come to Egypt to buy grain, and they do not recognize him. He keeps his secret, speaking roughly to them and hinting they may be spies. He allows them to leave only if they promise to return with their youngest brother Benjamin. He keeps Simeon as collateral but sends them off with full sacks of grain for their family. He also secretly returns their money, something they are terrified to discover on the way home. Back in Canaan, Jacob responds to this terrible news with bitterness and vindictive blame.