As you probably know, to convince Pharaoh to let the people go from Egypt, Moses commands ten plagues to come on the people (from God). These ten, in order, are: water turning to blood, frogs, lice, flies, livestock pestilence, boils, hail, locusts, darkness, and the death of the firstborn.
But we often forget that before those ten plagues, God used a few other signs: the turning of Moses’ staff into a serpent, and Moses’ hand turning white with leprosy. Most of us remember the staff, but, if I’m being honest, I always forget about the leprous hand.
Part of that reason is because the sign virtually disappears after the few verses it’s mentioned in Exodus 4:6-9. Moses doesn’t make his hand turn leprous (and back whole again) in Exodus 7, despite showing Pharaoh the rod-to-serpent sign.
Furthermore, Exodus 4:8-9 are explicit commands from God to show this particular sign when Pharaoh disbelieves in the serpent sign. Only then, God says, do you show the sign of the river turning into blood. So why didn’t Moses use it?
There are a few things we can point to to resolve this “issue.” First, there’s the simple fact that when Moses does go before Pharaoh in Exodus 7, it’s not even Moses that does the staff sign – it’s Aaron. So if we’re taking God’s command for Moses to show the sign ultra literally, Moses sinned in allowing Aaron to take his place.
I don’t think that’s what’s happening here. If you look back to Exodus 3:16-18, the very first audience for these signs is the heads of Israel, not Pharaoh. Yes, Moses will eventually talk to Pharaoh, but the first people you have to convince is Israel. Without their support, nobody’s going anywhere.
This interpretation changes the “they will not believe you” of Exodus 4:8 from Pharaoh to the Israelites. This argument is supported by the fact that God refers to the leprous hand as the “last sign,” which, as we know, is not the last sign that God would give to Pharaoh. Moreover, down in Exodus 4:30, the Text plainly says that Moses “performs these signs” for the heads of Israel.
Why didn’t Moses also show the sign of the leprous hand to Pharaoh? To be frank, it’s not a given that he didn’t. Just because the Bible doesn’t record this exact incident doesn’t mean that Moses didn’t show the sign – it’s just not recorded for us.
The real point of this sign is to show to the people that God has the ultimate control. Not only does He have control over nature by turning staffs into snakes, but He also has control over human flesh. And as the Ten Plagues reveal, He has control over basically everything else as well.