觀無量壽佛經疏 3.101

3.101

二、從諸佛如來下，至心想中已來，正明諸佛大慈，應心即現，有斯勝益故勸汝想之。

Second, from "The Buddhas, the Tathāgatas" down to "within the mental visualization" directly clarifies that the Buddhas have great compassion and manifest in response to the mind; because there is this supreme benefit, [the Buddha] encourages you to visualize them.