Step back and see the whole scene. In four short verses Matthew has begun to answer the question that will echo through the chapter until the disciples finally shout it in the storm, What sort of man is this? He is a King with authority to speak cleanness into a ruined body with a single word. He is a King who is not afraid of what defiles us. He is a King who answers our trembling if you will with a settled I will.
But this is more than a healing story from long ago. Leprosy in Scripture is a living picture of sin, and this touch on a Galilean hillside points forward to a greater hill outside Jerusalem. The great exchange we glimpse in Matthew 8 happened again at the cross, and there it happened forever. The clean one took our uncleanness upon himself. He bore it and carried it, as Isaiah 53 said he would. Paul puts it plainly. For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God. On Calvary the cleanness of Christ flowed down to cover the defilement of everyone who would come to him.
So if there is a part of your life you are certain is too far gone, if there is something you have never told a soul because you are sure it would make them back away, hear the King. You have probably never doubted that he is able. Hear this. He is also willing. He was willing to come down the mountain. He was willing to stretch out his hand. He was willing to go to the cross. You do not have to clean yourself up first; that leper did not. He came as he was, on his knees, honest about his need and sure of the power, and he walked away clean. For everyone who belongs to Christ, the verdict has already been spoken over you. Clean. Come to him, and live like it.