Exodus 15:26 And said, If thou wilt diligently hearken to the voice of the LORD thy God, and wilt do that which is right in his sight, and wilt give ear to his commandments, and keep all his statutes, I will put none of these diseases upon thee, which I have brought upon the Egyptians: for I am the LORD that healeth thee.
This is both a warning and a promise.
We must remember Whom we are dealing with, the Sovereign, Majestiic God who hates sin.
Deuteronomy 28:27 The LORD will smite thee with the botch of Egypt, and with the emerods, and with the scab, and with the itch, whereof thou canst not be healed.
Deuteronomy 28:35 The LORD shall smite thee in the knees, and in the legs, with a sore botch that cannot be healed, from the sole of thy foot unto the top of thy head.
Deuteronomy 32:39 See now that I, even I, am he, and there is no god with me: I kill, and I make alive; I wound, and I heal: neither is there any that can deliver out of my hand.
Let us fear to fall into hands of the Living God, but let us remember too that He is a mercitul God Who laid the punshment of our sin on His only begotten Son,
Let us come to Him in repentance as David did, as Aaron did and we will be healed, as Aaron's sister was healed.
Numbers 12:10 And the cloud departed from off the tabernacle; and, behold, Miriam became leprous, white as snow: and Aaron looked upon Miriam, and, behold, she was leprous.
11 And Aaron said unto Moses, Alas, my lord, I beseech thee, lay not the sin upon us, wherein we have done foolishly, and wherein we have sinned.
12 Let her not be as one dead, of whom the flesh is half consumed when he cometh out of his mother's womb.
13 And Moses cried unto the LORD, saying, Heal her now, O God, I beseech thee.
14 And the LORD said unto Moses, If her father had but spit in her face, should she not be ashamed seven days? let her be shut out from the camp seven days, and after that let her be received in again.
15 And Miriam was shut out from the camp seven days: and the people journeyed not till Miriam was brought in again.
The Lord dealt sternly with Miriam because she was one of the highest leaders of the land, but even in wrath, He was merciful and promised healing in seven days.