grinding.

Exodus 11:5
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.

Judges 16:21
Then the Philistines seized him, gouged out his eyes, and brought him down to Gaza, where he was bound with bronze shackles and forced to grind grain in the prison.