Jesus promptly sent him away with a stern warning:

Matthew 9:30
And their eyes were opened. Jesus warned them sternly, "See that no one finds out about this!"

Mark 1:42
And immediately the leprosy left him, and the man was cleansed.

Mark 1:44
"See that you don't tell anyone. But go, show yourself to the priest and present the offering Moses prescribed for your cleansing, as a testimony to them."

And he straightly charged him, and immediately sent him away;