妙法蓮華經玄義 4.97

4.97

云何如來座為天行？第一義天實相妙理，諸佛所師，一切如來同所栖息。文云：「觀一切法空，不動、不退，亦不分別上、中、下法，有為、無為，實、不實法。」故如來座即天行。

How does the Tathāgata's seat designate divine practice? The marvelous principle of the real mark of the paramārtha heaven is the teacher of all Buddhas, the identical resting place of all Tathāgatas. The text states: 'Contemplating all dharmas as empty, unmoving, non-regressing, neither discriminating superior, intermediate, nor inferior dharmas, conditioned or unconditioned, real or unreal dharmas.' Therefore, the Tathāgata's seat is divine practice.