Exodus 4:6

And the Lord said furthermore unto him, Put now thine hand into thy bosom. And he put his hand into his bosom: and when he took it out, behold, his hand was leprous as snow.

Cross-references

Numbers 12:10 describes Miriam struck with leprosy as white as snow – a similar divine use of leprosy as a sign, here as judgment.

Leviticus 13:2 defines the skin condition that appears on Moses' hand — the legal diagnosis of leprosy.