梵網經菩薩戒本疏 6.136

6.136

七、通塞者，癡狂、身當說法，若疑他大已便居下坐，若大眾坐定自後到來，校三五歲十四坐，並應無犯。反上皆結。

Seventh, permissibility and prohibition: If one is insane, if one is about to preach the Dharma, if one suspects that another is senior to oneself and so takes a lower seat, or if after the great assembly is seated one arrives later and takes a seat misjudging [seniority] by three, five, or fourteen years—in all such cases there should be no offense. Contrary to the above, all are adjudged offenses.