大方廣佛華嚴經隨疏演義鈔 19.26

19.26

疏「從自佛善根海生」者，由普賢等自圓十身，十身之中有如來身，依於佛身起菩薩用，云從彼生。

On the Commentary's "Born from the ocean of one's own Buddha's roots of goodness": because Samantabhadra and the others themselves fully complete the ten bodies, and among the ten bodies there is the Tathāgata body, relying on the Buddha body they give rise to bodhisattva functions, which is called being born from that.