四部律并論要用抄 2.47

2.47

掘地戒　善見論云。有真地非真地者。無沙石純土者名真地。若多有瓦石沙礫而土少名非真地。被燒地亦名非真地。若沙石地以水洮看　四分沙石一分土者。如是得自掘。石上土厚四寸。𤍜者可取。雨已逕四月不得取。

The precept against digging the earth: The Samantapāsādikā states: "There is genuine earth and non-genuine earth. That which has no sand or stone and is purely soil is called genuine earth. If there are many tiles, stones, sand, and gravel with little soil, it is called non-genuine earth. Earth that has been burned is also called non-genuine earth. If it is sandy or stony earth, examine it by washing it with water." According to the Caturvargika[-vinaya], if there is [gravel and] sand with one part soil, one may dig it oneself. If the soil on a rock is four inches thick, it may be taken if it is dry; once it has rained and four months have elapsed, it must not be taken.