John Gill Commentary Genesis 42:10

"And they said unto him, Nay, my lord, but to buy food are thy servants come." — Genesis 42:10 (ASV)

And they said to him, nay, my lord
One in the name of the rest, or each in his turn, denying that they were spies, and addressing him with the greatest reverence and submission, calling him their lord, and thus further accomplishing his dreams: but to buy food are your servants come ;
that and no other was the errand they came upon.