大乘起信論別記 1.191

1.191

言「以少分見法身故，隨其願力能現八相利益眾生」者，如《華嚴經》歎十住中初發心住菩薩云「此發心菩薩，得如來一身無量身，悉於一切世間，示現成佛故。」又《瑜伽論》云「彼及所餘，於無餘依涅槃界中般涅槃者，於十方界當知究竟不可思議。數數現作一切有情諸利益事，是名最極如來祕密。此祕密勝解行地修行菩薩，下忍轉時，隨其勝解差別而轉，從此轉勝乃至九地，展轉增進，第十地中最善清淨。當知如來如是祕密不可思議，超過一切度量境界。」如是等文，皆十解以上菩薩，能起八相之化物也。

Regarding "because they partially see the dharmakāya, according to the power of their vows they are able to manifest the eight aspects to benefit sentient beings": as the Avataṃsakasūtra praises the bodhisattva of the abode of initial cittotpāda among the ten abodes, saying: "This bodhisattva of cittotpāda attains the Tathāgata's single body and immeasurable bodies, manifesting the attainment of Buddhahood in all worlds." Also the Yogācārabhūmiśāstra states: "Those and the rest, who enter parinirvāṇa in the realm of nirvāṇa without remainder, should be known to be ultimately inconceivable in the realms of the ten directions. Frequently manifesting and performing all beneficial acts for sentient beings, this is called the supreme secret of the Tathāgata. Practicing bodhisattvas on the stage of engaging through resolute faith operate in this secret, when their lower patience turns, in accordance with the differences in their resolute faith; turning from this to become superior up to the ninth stage, they advance incrementally, and in the tenth stage it is most completely purified. One should know that such secrets of the Tathāgata are inconceivable, transcending all measured spheres." Passages such as these all refer to the transformation of beings through the ability to initiate the eight aspects by bodhisattvas from the ten understandings upward.