四分比丘戒本疏 2.31

2.31

第二十七、過前求過前用雨浴衣戒。此兩戒合制也。「春殘一月在」者，從正月半至四月半，合三箇月以為春時。春時之中殘一月在，即當三月十六日已去是也。故律云「三月十六日應求雨浴衣」也。「半月應用浴」者，三月十六日已去，數滿半月便是四月一日，故律云「四月一日應用浴」也。餘文易解。雨浴衣量，如下九十戒中。《薩婆多論》第六卷云「一者天雨時以障四邊，於中澡浴。若天熱時，亦以自障，於中澡浴。二者以夏多雨，當裹三衣擔持行來。」

Twenty-seventh: the precept against seeking a rainy-season bathing robe in advance of the proper time and using it in advance of the proper time. These two precepts are formulated together. 'When one month remains of spring': from the middle of the first month to the middle of the fourth month, three months in total make up the spring season. When one month remains within the spring season, that corresponds to from the sixteenth day of the third month onward. Therefore the Vinaya states: 'On the sixteenth day of the third month one should seek a rainy-season bathing robe.' 'For half a month one should use it to bathe': counting forward half a month from the sixteenth day of the third month brings one to the first day of the fourth month; therefore the Vinaya states: 'On the first day of the fourth month one should use it to bathe.' The remainder of the text is easy to understand. The measurements of the rainy-season bathing robe are as explained below in the ninety precepts. The sixth fascicle of the Sarvāstivāda-śāstra states: 'First, when it rains, one screens the four sides with it and bathes within it. When the weather is hot, one also screens oneself with it and bathes within it. Second, because in summer there is much rain, one should wrap up the three robes in it and carry them while travelling back and forth.'