Genesis 44:9

Of course such an accusation was a shock to the brothers. They protested that they would not think of such a thing. They had found the money in their sacks and brought it back. Surely that was proof they were not thieves. They are so confident of this that they say: if the silver cup is found with one of them, he should die, and the rest would be slaves to Joseph.

The steward approved of their words, but his own answer was far milder. Of course Joseph had instructed him. He tells them that the guilty one would be kept as a slave to Joseph and the rest could go free. The search began at the eldest, finishing with the youngest, in whose sack the silver cup was found. What a shock to them all! What a traumatic experience for Benjamin who knew himself innocent!

Joseph was here to carry out the test needed to clear up all the past mischief, and to form a new heart and a new spirit in his brothers. He did it for God's sake and for their sakes, not for his own, so that a work of God in their conscience and heart would be real and evident. This dictated the cup in Benjamin's sack. No doubt the shock of finding it there deeply troubled the brothers. But it had to be that way, because the deepest kind of sin lay under it all. This was only a means to make them feel it and judge it as they should.

Severe as the trial was, love dictated it in the fear of God, though we may feel that the mode adopted was in no way what the New Testament would suggest to the Christian… Scripture tells us the facts as they were, without sanction or apology.

Will the sorrows of Benjamin move them, as the cries of Joseph once failed to do? Will the grief of the aged father at home plead with their heart, as once it did not? This place, this moment, was the field of Dothan again. They were going back, in spirit, to the place where they had done all their wrong. In the field of Dothan, in Genesis 37, they had to answer one question: would they sacrifice their innocent brother Joseph to their lusts, their envy, and their malice? Here Benjamin is claimed as a captive, because the cup was found in his sack. He is claimed as a man who has forfeited life and liberty to the lord of Egypt. In the same way, they must now say whether they would sacrifice him, and go on their way home, easy and careless and satisfied.

They were innocent, indeed, as to the cup. But this is nothing to their consciences, and nothing on Judah's lips. Conviction loses sight of everything but sin. The offence is all it looks at. "For I know my transgressions, and my sin is ever before me." … They had once hidden their guilt under the lie they sent to their father. Now they are willing to hide their innocence about the cup under the confession they make to Joseph.

They were accused of stealing the cup, though they were guiltless of it. They declare that they are willing for the offender to die, and for the rest to be slaves in Egypt. … Now Judah, to save Benjamin, volunteers to be the slave in his place. He faces the very doom to which he had consigned Joseph. When this was reached, relief came.