"And the El Shaddai grant you mercy" (Genesis 43:14). Jacob is sending Benjamin to Egypt — his youngest, his only remaining connection to Rachel, the son he can least afford to lose. He has already sent ten sons and gotten back strange terms and a hostage. And now he has to send the one he was protecting. He says: God Almighty grant you mercy.
Psalm 139 provides the framework: "Knowledge is too formidable for me; it is concealed from me, I cannot know it" (Psalm 139:6). Jacob says something similar: "I cannot understand this matter." God had promised Abraham twelve tribes (Genesis 15:5). Jacob has twelve sons. But Joseph is apparently dead, and now Benjamin is being demanded as collateral. The math does not add up to the promise. Jacob cannot see how God will keep the covenant while simultaneously doing what seems to be happening.
The rabbis read this as the defining moment of Jacob's faith — not the dream at Bethel, not the wrestling at the Jabbok, but this. Sending the child you least want to send, in the direction you least trust, toward an outcome you cannot predict, with only God's prior promises to hold onto. "May God Almighty grant you mercy" is not a prayer of confidence. It is a prayer of someone who has run out of everything except the name of God. And the rabbis said: that is exactly enough.