He wants to know if they have repented or not. Reconciliation without repentance is like painting over the mold on a wall . Joseph knew there could be no real reconciliation with his brothers unless they addressed their behavior in the past. Throughout the Bible we read of the necessity for repentance. Repentance, as Christ preached it, is a changing of the mind, the intellect, the values that inevitably produces a profound change of the heart and emotions, a total radical transformation from seeking to please self to seeking to please God.
Repentance leads to nothing less than a human revolution.
Now that sounds simple enough. The brothers of Joseph sounded contrite. They seemed to be sorry early on. But Joseph couldn't conclude that they had genuinely repented. People Can Feel Sorry and not be repentant.