Mill

…and every firstborn son in the land of Egypt will die, from the firstborn of Pharaoh who sits on his throne, to the firstborn of the servant girl behind the hand mill, as well as the firstborn of all the cattle.

…when the doors to the street are shut and the sound of the mill fades away, when one rises at the sound of a bird and all the daughters of song grow faint,

Two women will be grinding at the mill: one will be taken and the other left.