Exodus 9:6-8

Young's Literal Translation

⁶ And Jehovah doth this thing on the morrow, and all the cattle of Egypt die, and of the cattle of the sons of Israel not one hath died;

⁷ and Pharaoh sendeth, and lo, not even one of the cattle of Israel hath died, and the heart of Pharaoh is hard, and he hath not sent the people away.

⁸ And Jehovah saith unto Moses and unto Aaron, `Take to you the fulness of your hands [of] soot of a furnace, and Moses hath sprinkled it towards the heavens, before the eyes of Pharaoh,