Commentaire sur La Genèse 42:11

כלנו בני איש אחד נחנו WE ARE ALL ONE MAN’S SONS — The Holy Spirit was enkindled in them and they included him with themselves (by using the word “We”) that he, also, was the son of their father (Genesis Rabbah 91:7).

WE ARE ALL ONE MAN’s SONS. It is possible to explain this plea as follows: They said that “since we are brothers, one man’s sons, who do not separate from each other for such is our father’s will, we all came to buy food, and we did not send one of us with his servants.” This indeed was the truth, for why should Jacob have sent them all, except that it was not their wish to be separated from one another. It is also possible that they did so because of the extreme famine, lest the grain brought by their servants be robbed from them on the way.
It is also possible that they said to him: “We are all one man’s sons. You can investigate him, for he is known in the gates by the vastness of his wealth and the multitude of his children. And if you will inquire and investigate, you will know that we are trustworthy, righteous men, sons of a righteous one, and not spies.”

כולנו בני איש אחד נחנו, this is why we always keep together, not because we are spies.