Shemot 11:5-6

And all the bechor in Eretz Mitzrayim shall die, from the bechor Pharaoh that sitteth upon his kisse, even unto the bechor hashifchah that is behind the millstone; and all the bechor behemah. And there shall be a great cry throughout kol Eretz Mitzrayim, such as there was none like it, nor shall be like it any more.