the red material that forms on metal. Rust eats away at metal and eventually destroys it
## Take ##
Yahweh does not give this command to a specific person, instead he is commanding some imaginary person who is part of the metaphor.
## but do not cast lots for it ##
Casting lots was a way of choosing which pieces of meat to take out, but because Yahweh wants to take out all of the pieces of meat, there is no need to cast lots.