Behold, to morrow about this time I will cause it to rain a very grievous hail, such as hath not been in Egypt since the foundation thereof even until now.

Wesley's Notes

9:18 Since the foundation thereof - Since it was a kingdom.

Jamieson-Fausset-Brown Bible Commentary

Ex 9:18-35. Plague of Hail.

18. I will cause it to rain a very grievous hail, &c.-The seventh plague which Pharaoh's hardened heart provoked was that of hail, a phenomenon which must have produced the greatest astonishment and consternation in Egypt as rain and hailstones, accompanied by thunder and lightning, were very rare occurrences.

such as hath not been in Egypt-In the Delta, or lower Egypt, where the scene is laid, rain occasionally falls between January and March-hail is not unknown, and thunder sometimes heard. But a storm, not only exhibiting all these elements, but so terrific that hailstones of immense size fell, thunder pealed in awful volleys, and lightning swept the ground like fire, was an unexampled calamity.

Matthew Henry's Concise Commentary

9:13-21 Moses is here ordered to deliver a dreadful message to Pharaoh. Providence ordered it, that Moses should have a man of such a fierce and stubborn spirit as this Pharaoh to deal with; and every thing made it a most signal instance of the power of God has to humble and bring down the proudest of his enemies. When God's justice threatens ruin, his mercy at the same time shows a way of escape from it. God not only distinguished between Egyptians and Israelites, but between some Egyptians and others. If Pharaoh will not yield, and so prevent the judgment itself, yet those that will take warning, may take shelter. Some believed the things which were spoken, and they feared, and housed their servants and cattle, and it was their wisdom. Even among the servants of Pharaoh, some trembled at God's word; and shall not the sons of Israel dread it? But others believed not, and left their cattle in the field. Obstinate unbelief is deaf to the fairest warnings, and the wisest counsels, which leaves the blood of those that perish upon their own heads.