法華玄論 2.130

2.130

十三者明此華必生於菓，餘華不爾或生不生，喻一乘之因必當作佛，三乘之因或作或不作。

Thirteenth, it clarifies that this flower must produce fruit, whereas other flowers are not like this, sometimes producing fruit and sometimes not; this illustrates that the cause of the one vehicle will definitely attain Buddhahood, while the causes of the three vehicles may or may not do so.