四分戒本疏卷第一．第二．第三 3.17

3.17

實得道向未受具戒人說戒第八　論云。二義故制。一為大人法故。理宜功德覆藏諸惡發露。今自說德行隱匿罪過非大人之法。二自顯聖德。則賢愚有異。前人聞之。偏心專敬。失於平等淨善之心。是故聖制　別緣有五。一內有實德蠲去增上慢人境虛不犯。二自言己有。三向未受具人說。四言辭了了。五前人聞知。然復此戒不別有緣。舉大妄語中。或有實得音以制斯戒。此聖人制竟不復更犯。謂是制聖遮凡。

The eighth precept: speaking of one's actual attainment of the path to an unordained person.
The treatises say that it was instituted for two reasons: First, for the sake of the practice of great beings. It is proper in principle to conceal merit and expose offenses. To now speak of one's own virtuous conduct while hiding one's faults is not the practice of great beings. Second, by displaying one's noble virtues oneself, a distinction is drawn between the worthy and the foolish; when the other person hears of it, their mind becomes partial and devoted [only to that individual], losing the equal, pure, and wholesome mind. Therefore the Sage instituted it.
There are five specific conditions: 1. having actual virtues within—[this condition] excludes those with excessive pride, [and if] the object is unreal, there is no offense; 2. stating them to be one's own; 3. speaking to an unordained person; 4. clear speech; 5. the other person hearing and understanding. Moreover, this precept has no separate origin story; it was formulated based on the [formulation of the rule against] grave false speech, where some had actually attained [the states]. Once instituted by the Sage, no noble being ever violated it again; this means it was instituted to guide the noble and prevent ordinary persons [from doing so].