“May God Almighty give you mercy as you go before the man… But if I must lose my children, so be it.”
Jacob was distraught to hear that he must let Benjamin go back to Egypt with his brothers, for Joseph (the “man” Jacob refers to) had insisted upon it.
The situation was out of his control, and so he appeals to God Almighty for mercy. Along with that appeal, there is an acknowledgement of God’s sovereignty – “…so be it”.
