And the Lord spake unto Moses,.... Pharaoh still being obstinate, and refusing to let the people go: say unto Aaron, take thy rod, and stretch out thine hand upon the waters of Egypt; upon all of them in general, what were in the river Nile, or derived from it, as follows: upon their streams; the seven streams of the river Nile; see Gill on Isa 11:15. upon their rivers; the canals that were cut out of the river Nile, for the watering of their fields and gardens, for they had no other river: and upon their ponds, and upon all their pools of waters; which were dug near the river, or to which pipes were laid to convey the water thither: that they may become blood; and so not fit to drink: and that there may be blood throughout all the land of Egypt, both in vessels of wood, and in vessels of stone; in which water were kept in private houses, fetched from the river for the use of families; all which were to be turned into blood everywhere, in all parts of the land, and in all places mentioned, immediately upon Aaron's taking his rod, and smiting the waters with it in that part of the river that was before him.