When Yosef saw his brothers, he recognized them; but he acted like a stranger toward them and spoke harshly to them. He asked them, “Where do you come from?” And they said, “From the land of Canaan, to procure food.” GENESIS 42:7 (The Israel Bible™)
Many commentators point out the incongruity between Yosef’s question and the brothers’ answer. Yosef asked only about their origin; why, then, did the brothers supply a reason for their travels? The question is strengthened by the fact that assumedly, their reason for coming to Egypt was self-evident. Rabbi Zalman Sorotzkin answers that the brothers were accustomed to the need to apologize and offer an explanation for leaving the holy Land of Israel. Although they could presume that the Egyptian would not think in these terms, they nevertheless felt the need to excuse their absence from their spiritual homeland.