一切經音義 11.266

11.266

如砥掌（上音止孔注尚書砥細於礪皆磨石也砥掌喻平也）。

如砥掌 [flat as a whetstone or palm] (The first is pronounced 止. Kong [Anguo's] commentary on the Shangshu says: "A *di* is finer than a *li*; both are whetstones." "Like a whetstone or palm" is a metaphor for flatness).