四分律行事鈔資持記 2.1131

2.1131

不犯有六。初是想差，如稠粥作稀想；二即上行，永無有犯；三約食體不淨（或前食非正）；四即病緣；五謂已殘；六是順教。（儉開不作，文無理有。）

There are six non-offenses: First, mistaken perception, such as taking thick gruel to be thin gruel; second, the higher practice, which is forever free of offense; third, based on the food-substance being impure (or the prior food not being principal food); fourth, the circumstance of illness; fifth, being already made leftover; sixth, following the teaching. (The exception not to perform it during famine is present in principle, though absent in text.)