妙法蓮華經玄義 6.107

6.107

尼陀那者，說諸佛本起因緣，佛何因緣說此事？脩多羅中，有人問故為說是事；毘尼中，有人犯是事故結是戒。一切佛語緣起事，皆名尼陀那。

As for *nidāna*, it speaks of the original causal conditions of the Buddhas: for what causal condition did the Buddha speak of this matter? In the sūtras, he spoke of a matter because someone asked; in the vinaya, he formulated a precept because someone committed an offence. All matters concerning the conditioned arising of the Buddha's words are named *nidāna*.