《新唐书·列传·卷一百四十七》
人民七岁时剃发到寺庙里去学习，直到二十岁，如果仍不通达佛法的就再当老百姓。
民七岁祝发止寺，至二十有不达其法，复为民。
At the age of seven, the people shave their hair and go to the temple to study until they are twenty years old. If they still do not understand Buddhism, they will become common people again.