大毘盧遮那成佛神變加持經 (Shubhakarasimha & Yixing 724) 2.6

2.6

“The Buddhas are exceedingly rare, their expedient wisdom inconceivable;
free from all proliferation of conceptual elaborations, the spontaneous wisdom of the Buddhas
is expounded for the sake of the world, fulfilling the many hopes and wishes.
The characteristics of mantras are like this, always relying on the two truths.
If there be sentient beings who understand this teaching of the Dharma,
people of the world should make offerings to them, just as they venerate a caitya.”