The Lord shall sever - See Clarke on Exodus 8:22 (note).

And the Lord shall sever between the cattle of Israel and the cattle of Egypt,.... Make such a difference and distinction between them, that the murrain should not be on the one, when it was on the other, and which was a very marvellous thing; and especially in the land of Goshen, where the Egyptians had much cattle, and Pharaoh himself, see Genesis 47:6 and yet, though the cattle of Israel breathed in the same air, drank of the same water, and fed in the same pastures, they had not the murrain as the cattle of Egypt had; and the word here used signifies a marvellous separation, as has been observed on Exodus 7:22,

and there shall nothing die of all that is the children's of Israel; not an horse, nor an ass, nor an ox, nor a sheep.

And the LORD shall {a} sever between the cattle of Israel and the cattle of Egypt: and there shall nothing die of all that is the children's of Israel.

(a) He will declare his heavenly judgment against his enemies, and his favour toward his children.

9:1-7 God will have Israel released, Pharaoh opposes it, and the trial is, whose word shall stand. The hand of the Lord at once is upon the cattle, many of which, some of all kinds, die by a sort of murrain. This was greatly to the loss of the owners; they had made Israel poor, and now God would make them poor. The hand of God is to be seen, even in the sickness and death of cattle; for a sparrow falls not to the ground without our Father. None of the Israelites' cattle should die; the Lord shall sever. The cattle died. The Egyptians worshipped their cattle. What we make an idol of, it is just with God to remove from us. This proud tyrant and cruel oppressor deserved to be made an example by the just Judge of the universe. None who are punished according to what they deserve, can have any just cause to complain. Hardness of heart denotes that state of mind upon which neither threatenings nor promise, neither judgements nor mercies, make any abiding impression. The conscience being stupified, and the heart filled with pride and presumption, they persist in unbelief and disobedience. This state of mind is also called the stony heart. Very different is the heart of flesh, the broken and contrite heart. Sinners have none to blame but themselves, for that pride and ungodliness which abuse the bounty and patience of God. For, however the Lord hardens the hearts of men, it is always as a punishment of former sins.