大乘義章 12.116

12.116

八戒齊者，所謂不殺、不盜、不婬、不妄語、不飲酒、不歌舞唱伎、不著香薰衣、不上高廣床、不過中食，是其名也。此等防禁故名為戒，潔清曰齊。問曰：於彼五戒之中言不邪婬今此何故直言不婬？釋言：五戒是在家人持在家戒，唯制邪婬，不防自妻。以是義故，但言不邪。婬論八戒，是在家人得持出家戒，非但制邪，自妻亦防，故說不婬。問曰：是中所離有九，以何義故但言八戒？釋言：有以。若依《毘曇》，不著薰衣、不上高床，此二同是莊嚴處起，合之為一，故說為八。若依《成實》及《大智論》，前八是戒，後一是齊。戒齊合說。是故名為八戒齊矣（此一門竟）。

Regarding the eightfold fasting precepts: they are non-killing, non-stealing, celibacy (non-unchastity), non-false speech, non-drinking of alcohol, non-singing, dancing, and theatricals, non-wearing of scents and perfumed clothing, non-using of high and broad beds, and non-eating past noon—these are their names. Restraining against [faults] like these is therefore called 'precepts' (śīla), and purification is called 'fasting' (upoṣadha). Question: In the five precepts it says 'non-misconduct in sexual desires,' so why does it here directly say 'celibacy' (non-unchastity)? Explanation: The five precepts are observed by laypeople as lay precepts, which only prohibit misconduct in sexual desires and do not restrain [intercourse with] one's own spouse. For this reason, it only says 'non-misconduct.' Concerning the eight precepts, they are monastic precepts that laypeople are able to observe; they not only prohibit misconduct, but also restrain [intercourse with] one's own spouse, and thus it is spoken of as celibacy. Question: Here the items to be abandoned are nine; for what reason are they only spoken of as eight precepts? Explanation: There is a reason. If according to the Abhidharma, not wearing perfumed clothing and not using high beds both arise from bodily adornment and are combined into one, hence they are spoken of as eight. If according to the Tattvasiddhi and the Mahāprajñāpāramitopadeśa, the former eight are precepts and the last one is the fast; the precepts and fast are spoken of together, and therefore they are called the eightfold fasting precepts (this concludes the first gate).