妙法蓮華經玄義 6.135

6.135

因緣者，結緣覆講大乘，繫珠不論小乘人天等緣，是名因緣妙也。

As for nidāna (causes and conditions): forming conditions and re-expounding the Mahāyāna, tying the jewel [in the hem] without discussing conditions of the small vehicle, humans, or devas; this is called the subtlety of nidāna.