Immediately the leprosy left him, and he was made clean. After sternly warning him he sent him away at once, saying to him, ‘See that you say nothing to anyone; but go, show yourself to the priest, and offer for your cleansing what Moses commanded, as a testimony to them.’ But he went out and began to proclaim it freely, and to spread the word, so that Jesus could no longer go into a town openly, but stayed out in the country; and people came to him from every quarter. (Mark 1: 42-45)

Jesus warns the leper to behave in accordance with the law of Moses, showing himself to the priest. Scripture specifies a way for a priest to confirm that leprosy has been healed.

He also warns the leper to "say nothing to anyone" presumably regarding the source of his healing.

The purpose of Jesus in this regard is unclear. He has already impressed the synagogue crowd by ordering the unclean spirits to leave a man. The opportunity to hide such healings is past.

The original Greek suggests, at least to me, a possibility. Lego medeis hupago deiknuo is the core phrase: "Say nothing, go show" is close to a literal translation.

Don't spend so much talking about your relationship with God, demonstrate its meaning in what you do.

The leprosy left immediately, another application of euthus. Jesus also sent away the leper "immediately."

Above is Hiroshima 1961 by Yves Klein.