釋氏要覽 2.302

2.302

智論問云。諸床可坐。何必蓮華。答諸床為世間白衣坐法。又蓮華濡淨柔脆。欲現神力。能坐其上。令華不壞故。又以莊嚴妙法座故。

The Mahāprajñāpāramitōpadeśa asks: Any couch may be sat upon, so why must it be a lotus? The answer states: Various couches are the seating manner of worldly laypeople. Furthermore, the lotus is soft, pure, delicate, and fragile; wishing to display divine power, he can sit upon it while causing the flower not to break. Also, it is to adorn the wondrous Dharma seat.