If you will give earnest heed to the voice of the LORD your God, and do what is right in His sight, and give ear to His commandments, and keep all His statutes, I will put none of the diseases on you which I have put on the Egyptians; for I, the LORD, am your healer. (Exodus 15:26).
You shall keep the commandment and the statutes and the judgments which I am commanding you today, to do them. Then it shall come about, because you listen to these judgments and keep and do them, that the LORD your God will keep with you His covenant and His lovingkindness which He swore to your forefathers. And He will love you and bless you…And the LORD will remove from you all sickness, and He will not put on you any of the harmful diseases of Egypt which you have known, but He will lay them on all who hate you. (Deuteronomy 7:11-13,15).
[Christ] has obtained a more excellent ministry, by as much as He is also the mediator of a better covenant, which has been enacted on better promises. (Hebrews 8:6).
See also James 5:13-16.