Gen 42 – Reuben’s pledge to his father backfires on him. Joseph tests his brothers.

Gen 42:36
And their father Jacob said to them, "You have bereaved me of my children: Joseph is no more, and Simeon is no more, and you would take Benjamin; all these things are against me."

Gen 42:37
Then Reuben spoke to his father, saying, "You may put my two sons to death if I do not bring him back to you; put him in my care, and I will return him to you."

Reuben makes a pledge to his father that he will return with Benjamin. It is one that backfires on him.

Gen 42:38
But Jacob said, "My son shall not go down with you; for his brother is dead, and he alone is left. If harm should befall him on the journey you are taking, then you will bring my gray hair down to Sheol in sorrow."

Jacob says that Benjamin alone is left. He means that Benjamin is all he has left of his beloved wife Rachel, whom he greatly loved. Jacob says "no."