Rashi on Genesis 42:19/רש"י על בראשית מ״ב:י״ט

1בבית משמרכם (literally, in the house of your ward) — the house in which you are at present imprisoned.

2ואתם לכו הביאו BUT YE, GO, CARRY to your father’s house.

3שבר רעבון בתיכם CORN FOR THE FAMINE OF YOUR HOUSES — what you have purchased for the hunger of the people in your houses.