Behold, the hand of the LORD is upon thy cattle which is in the field, upon the horses, upon the asses, upon the camels, upon the oxen, and upon the sheep: there shall be a very grievous murrain.

Wesley's Notes

9:3 The hand of the Lord - Immediately, without the stretching out of Aaron's hand, is upon the cattle, many of which, some of all kinds, shall die by a sort of pestilence. The hand of God is to be acknowledged even in the sickness and death of cattle, or other damage sustained in them; for a sparrow falls not to the ground without our father. And his providence is to be acknowledged with thankfulness in the life of the cattle, for he preserveth man and beast, Psa 36:6.

Jamieson-Fausset-Brown Bible Commentary

3-5. Behold, the hand of the Lord is upon thy cattle-A fifth application was made to Pharaoh in behalf of the Israelites by Moses, who was instructed to tell him that, if he persisted in opposing their departure, a pestilence would be sent among all the flocks and herds of the Egyptians, while those of the Israelites would be spared. As he showed no intention of keeping his promise, he was still a mark for the arrows of the Almighty's quiver, and the threatened plague of which he was forewarned was executed. But it is observable that in this instance it was not inflicted through the instrumentality or waving of Aaron's rod, but directly by the hand of the Lord, and the fixing of the precise time tended still further to determine the true character of the calamity (Jer 12:4).

Matthew Henry's Concise Commentary

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.