大毘盧遮那成佛經疏 2.40

2.40

第十一「云何積聚心？謂無量為一為性」者，謂此人隨於一事生信解已，更聞種種殊異法，皆合集為一。如人學得一三昧已，見餘經教無量法門差別勝事，皆謂說此定心，離此之外更無餘法，故名積聚心也。

Eleventh: regarding "What is the accumulating mind? It has as its nature making the immeasurable into one": this means that after this person has given rise to faith and understanding regarding a single matter, when they further hear various distinct dharmas, they gather them all into one. For example, when a person has learned and attained a single samādhi, seeing the distinct, superior matters of the immeasurable Dharma-gateways in other sūtra teachings, they claim they all speak of this mind of meditative concentration, and that apart from this there are no other dharmas; hence it is called the accumulating mind.