Genesis 42:13

And they said, Thy servants are twelve brethren, the sons of one man in the land of Canaan; and, behold, the youngest is this day with our father, and one is not. Joseph's refusal to believe their assurance of innocence brings him the further information that his aged father is still alive, and that Benjamin is well at home. Their non-committal manner in referring to Joseph shows that they bore uneasy consciences on his account, but they could say no more to the Egyptian ruler.