四分律比丘含注戒本 1.183

1.183

當應量作。是中量者，長十二佛磔手，內廣七磔手。當將諸比丘指授處所，

he must make it according to the measure. Herein the measure is: twelve spans of the Buddha in length, and seven spans wide inside. He must bring the bhikṣus to mark out the site;