四分律行事鈔資持記 3.84

3.84

四中。謂五條身著，七條敷床上，大衣作枕，故云臥七條中。今恐損污，但著五條臥坐具上；七條大衣，襵揲頭所。

In the fourth [part], this means the five-strip robe is worn on the body, the seven-strip robe is spread on the bed, and the great robe is used as a pillow; hence it says 'lying within the seven-strip robe'. Nowadays, out of fear of damage and defilement, one only wears the five-strip robe while lying on the sitting mat, while the seven-strip robe and great robe are folded and placed at one's head.