Rashi on Genesis 42:13/רש"י על בראשית מ״ב:י״ג

1'ויאמרו שנים עשר עבדיך וגו AND THEY SAID, THY SERVANTS WERE TWELVE BRETHREN — [AND ONE IS NO MORE], and it is on account of that one who is no more that we dispersed ourselves through the city in order that we might search for him (Genesis Rabbah 91:6).