四分比丘戒本疏 2.107

2.107

第八十七、過量坐具戒。文舉初制，長佛二搩、廣一搩半。後因迦留陀夷身大嫌小，佛開廣長各半搩手，合是二半及二也，計長五尺、闊四尺也。作坐具法，兩複安褋、四周安緣，一長一短如五條相，名為割截。今時不行此法也。

Eighty-seventh, the precept on an oversized sitting-cloth (niṣīdana). The text mentions the initial regulation: two spans of the Buddha in length and one and a half spans in width. Later, because Kāḷudāyin had a large body and disliked it being small, the Buddha permitted adding half a span each to the width and length, making two and a half and two [spans] respectively, which calculates to five chi in length and four chi in width. The method of making a sitting-cloth: apply a patch to two layers and attach a border on all four sides, with one long and one short strip like the markings of a five-strip robe, which is called 'cut and stitched' (chinnaka). Nowadays, this method is no longer practiced.