And the LORD will take away from thee all sickness, and will put none of the evil diseases of Egypt, which thou knowest, upon thee; but will lay them upon all them that hate thee.

Wesley's Notes

7:15 The diseases of Egypt - Such as the Egyptians were infected with, either commonly, or miraculously. It seems to refer not only to the plagues of Egypt, but to some other epidemic disease, which they remembered to have prevailed among the Egyptians, and by which God had chastised them for their national sins. Diseases are God's servants, which go where he sends them, and do what he bids them.

Jamieson-Fausset-Brown Bible Commentary

15. the evil diseases of Egypt-(See Ex 15:26). Besides those with which Pharaoh and his subjects were visited, Egypt has always been dreadfully scourged with diseases. The testimony of Moses is confirmed by the reports of many modern writers, who tell us that, notwithstanding its equal temperature and sereneness, that country has some indigenous maladies which are very malignant, such as ophthalmia, dysentery, smallpox, and the plague.

Matthew Henry's Concise Commentary

7:12-26 We are in danger of having fellowship with the works of darkness if we take pleasure in fellowship with those who do such works. Whatever brings us into a snare, brings us under a curse. Let us be constant to our duty, and we cannot question the constancy of God's mercy. Diseases are God's servants; they go where he sends them, and do what he bids them. It is therefore good for the health of our bodies, thoroughly to mortify the sin of our souls; which is our rule of duty. Yet sin is never totally destroyed in this world; and it actually prevails in us much more than it would do, if we were watchful and diligent. In all this the Lord acts according to the counsel of his own will; but that counsel being hid from us, forms no excuse for our sloth and negligence, of which it is in no degree the cause. We must not think, that because the deliverance of the church, and the destruction of the enemies of the soul, are not done immediately, therefore they will never be done. God will do his own work in his own method and time; and we may be sure that they are always the best. Thus corruption is driven out of the hearts of believers by little and little. The work of sanctification is carried on gradually; but at length there will be a complete victory. Pride, security, and other sins that are common effects of prosperity, are enemies more dangerous than beasts of the field, and more apt to increase upon us.