Joseph saw them and recognised them, but they did not know him. He was about seventeen at the time he was sold into slavery, and his face would have changed now that he was about thirty-nine.
All of Joseph’s dealings with his brothers may be taken as typical of Christ’s dealings with an approaching sinner. So Christ may treat those who come to him roughly at first but his intention is always to save his people. To the Syrophoenician woman Christ said, ‘It is not meet to take the children's bread, and to cast it to dogs (Matthew 15:26), but at the outcome he comforted her: ‘O woman, great is thy faith: be it unto thee even as thou wilt’ (Matthew 15:28). He does not do it out of unkindness, but with a wonderful objective in mind. Need we then be surprised that we also who need to be trained up and delivered from many snares, must pass through many experiences which are hard to understand. They are hard because the Lord means them to be hard. But by faith we believe always in God’s goodness and mercy, and know that when we have seen all things, his ways of dealing with us will be seen to have worked for our good.
Was Joseph guilty of deception when he accused them of being spies? No, it is an accusation which he knows they are not guilty of, but it is not a lie. It was not deceitful of him to behave as he did. It was instead necessary in order to teach them what God wanted to teach them. He is under no obligation to say that he knows them.