A.T. Robertson Commentary Matthew 8:2

"And behold, there came to him a leper and worshipped him, saying, Lord, if thou wilt, thou canst make me clean." — Matthew 8:2 (ASV)

If thou wilt (εαν θεληις). The leper knew that Jesus had the power to heal him. His doubt was about his willingness. "Men more easily believe in miraculous power than in miraculous love" (Bruce). This is a condition of the third class (undetermined, but with prospect of being determined), a hopeful doubt at any rate. Jesus accepted his challenge by "I will." The command to "tell no one" was to suppress excitement and prevent hostility.