觀無量壽佛經疏 4.10

4.10

四、從何等為三下，至必生彼國已來，正明辨定三心以為正因。即有其二。一明世尊隨機顯益意密難知，非佛自問自徵無由得解。二明如來還自答前三心之數。

Fourth, from "What are the three?" down to "they will certainly be born in that land", it directly clarifies and determines the three minds as the correct cause. There are two points: first, clarifying that because the World-Honoured One reveals the benefits in accordance with beings' capacities, his inner intention is profound and difficult to know, such that without the Buddha himself asking and investigating, there would be no way to understand it; second, clarifying that the Tathāgata in turn answers himself the number of the aforementioned three minds.