律戒本疏 1.34

1.34

十三應用二分純黑羚羊毛　既不聽純。開其雜也。雜既易得。入貪著心薄故聽也。異色二分。白色半之下。下者半之腹脚邊毛為下也。上黑色長一兩捨墮。下色少一兩墮。白色少一兩突吉也。

Thirteenth: One should use two parts of pure black sheep's wool. Since pure [black] is not permitted, mixing it is opened. Being mixed, it is easy to obtain, and the mind of greed and attachment enters lightly; therefore it is permitted. Two parts of a different colour: white is half of the lower part; "lower" refers to the wool from the belly and leg edges as the lower. If the upper black exceeds by one liang, it is a niḥsargika-pāyattika; if the lower colour is short by one liang, it is a pāyattika; if the white colour is short by one liang, it is a duṣkṛta.