Shemot 7:19

19 And Hashem spoke unto Moshe, Say unto Aharon, Take thy matteh, and stretch out thine yad upon the mayim of Mitzrayim, upon their streams, upon their rivers, and upon their ponds, and upon all their mikveh of mayim, that they may become dahm; and that there may be dahm throughout kol Eretz Mitzrayim, both in vessels of wood, and in vessels of stone.