Exodus 7:19
18 Fish in the Nile will die, the Nile will stink, and the Egyptians will be unable to drink water from the Nile.”’” 19 Then the Lord said to Moses, “Tell Aaron, ‘Take your staff and stretch out your hand over Egypt’s waters—over their rivers, over their canals, over their ponds, and over all their gathered waters43—so that it becomes blood.’ There will be blood everywhere in the land of Egypt, even in wooden and stone containers.” 20 Moses and Aaron did so, just as the Lord had commanded. He raised the staff and struck the water that was in the Nile right before the eyes of Pharaoh and his servants, and all the water that was in the Nile was turned to blood.
Exodus 9:23
22 Then the Lord said to Moses, “Extend your hand toward the sky that there may be hail in all the land of Egypt, on people and on animals, and on everything that grows in the field in the land of Egypt.” 23 When Moses extended his staff toward the sky, the Lord sent thunder and hail, and fire fell to the earth; so the Lord caused hail to rain down on the land of Egypt. 24 Hail fell and fire mingled with the hail; the hail was so severe that there had not been any like it in all the land of Egypt since it had become a nation.
Notes and References
"... P was written as an alternative to JE. The JE stories regularly said: 'And Yahweh said unto Moses. . . . ' ' But the author of P often made it: 'And Yahweh said unto Moses and unto Aaron ...' In JE, miracles are performed in Egypt using Moses' staff. But the author of P made it Aaron's staff. In JE, Aaron is introduced as Moses' 'Levite brother.' This would only mean that the two are fellow members of the tribe of Levi, not that they are literally brothers. But the author of P states categorically that Aaron and Moses were brothers, sons of the same mother and father, and that Aaron was the firstborn ..."
Friedman, Richard Elliott Who Wrote the Bible? (pp. 190-191) Harper San Francisco, 1997