四分比丘戒本疏 2.23

2.23

第十五、不六坐具戒。「一搩手」者，《多論》第五云「周匝修伽陀一搩手也。」「壞色」者，壞却新色，令離貪著。若准《僧祇》自無故者，從他求之。今准此律，若自無故者，不揀不犯也。

Fifteenth: the precept regarding the border of the sitting mat. "One span": the fifth fascicle of the Sarvāstivāda-śāstra states, "It is one Sugata span around the perimeter." "Disfiguring the colour": spoiling the new colour to cause detachment from greed. According to the Mahāsāṃghika, if one does not have an old one oneself, one seeks it from another. In accordance with this Vinaya, if one does not have an old one oneself, omitting it incurs no offence.