Genesis 44:29
And if ye take this also from me, and mischief befall him, ye shall bring down my gray hairs with sorrow to the grave. And if ye take this also from me, and mischief befall him, ye shall bring down my gray hairs with sorrow to the grave.
The verse records Jacob's warning that if Benjamin is taken from him and any harm comes to him, the resulting sorrow will bring down his gray hairs to the grave. He felt this so deeply because his own life was bound up in the lad's life. Benjamin was the last and only son still left to him by Rachel, the wife he loved. Jacob had already lost Joseph and had grieved greatly over that loss, which made the possible loss of Benjamin still heavier.
Benjamin was the youngest son still with Jacob, and his other sons were afraid to add sorrow to their father by exposing Benjamin to danger. Judah had made himself surety for Benjamin, pledging to bear the blame forever if he failed to bring the boy back to his father. Judah repeated Jacob's words to Joseph to explain that Benjamin's absence would cause their father to die of sorrow. He nobly pleaded to remain as a bondman in Benjamin's place and let Benjamin go up with his brethren, because he could not meet his father without Benjamin with him.
When the cup was found in Benjamin's sack, the brothers believed the feared danger had now come upon the much-loved Benjamin and their father's warning was about to be fulfilled.