Rashi on Exodus 12:33/רש"י על שמות י״ב:ל״ג

1כלנו מתים WE ARE ALL DEAD MEN — They said, Not according to Moses’ decree is this what has happened for he said (10:5) “And every firstborn shall die”, and here all the ordinary people are dead, five or ten in one house (Mekhilta).