Genesis 42:3-4

"And Joseph's ten brethren went down to buy grain from Egypt. But Benjamin, Joseph's brother, Jacob sent not with his brethren; for he said, Lest peradventure harm befall him."

Benjamin had become Jacob's favorite following what he supposed was the death of Joseph, and he might have been afraid that the same kind of hatred that had previously resulted from his partiality to Joseph might possibly have been transferred to Benjamin. There might even be some evidence here that Jacob in the intervening years had come to question some of the things his sons had told him. In any event, he refused to entrust Benjamin to them on this trip to Egypt.