說無垢稱經疏 6.436

6.436

贊曰：此花香供養。有二：初供養三尊、後散遍世界。如文可知。有法之處，如佛塔廟，理須供養。況表佛土本所唯淨，亦表有情滅煩惱惡，故覆於地。足可修行法性等益，故深沒膝。

The Commentary states: This is making offerings of flowers and incense. It has two parts: first, offering to the Three Honoured Ones; second, scattering them over the entire world. This is clear from the text. A place where the Dharma resides is like a stūpa or temple of the Buddha; in principle it should be given offerings. Furthermore, it symbolizes that the Buddha realm is originally purely clean, and also symbolizes that sentient beings extinguish the evils of affliction; hence they cover the ground. That they are sufficient for practicing the benefit of the Dharma-nature and so forth, they sink knee-deep.