Whetstone /(?)/

Whet·stone

Whetstone

n.
  1. A piece of stone, natural or artificial, used for whetting, or sharpening, edge tools.
    The dullness of the fools is the whetstone of the wits.
    Diligence is to the understanding as the whetstone to the razor.

Phrases & Compounds
To give the whetstone
to give a premium for extravagance in falsehood.