What does Genesis 42:38 mean?

But Jacob said, 'My son isn’t going down there with you. His brother is already dead, and he’s the only one I have left from Rachel. If something happens to him on the way, you’ll send me to my grave in misery.' Genesis 42:38 - Modern Text Bible

(Jacob refuses to let Benjamin go, because he’s terrified of losing the last son of his beloved wife Rachel. He’s still grieving Joseph and can’t bear the thought of another loss.)