摩訶止觀 6.164

6.164

其意者，三藏中菩薩偏用世智照俗；二乘偏用析假入真；佛二諦周足，異於弟子，假設第三觀。設作離有離無之說，秖是離有、無二見，實無別理可觀，故不須第三觀也。

Regarding its intention: in the Tripiṭaka [teaching], the bodhisattva exclusively uses worldly wisdom to illuminate the conventional; the two vehicles exclusively use the analysis of the provisional to enter the true; the Buddha is complete and fully endowed with the two truths, differing from his disciples, and hypothetically sets up a third contemplation. Even if he gives an exposition of leaving behind existence and leaving behind non-existence, it is merely leaving behind the two views of existence and non-existence, and there is genuinely no separate principle to contemplate; therefore, a third contemplation is not needed.