大方廣佛華嚴經隨疏演義鈔 72.36

72.36

疏「真如是佛行處」者，今此九地入向十地，何名入如來所行？答：十地同佛，境相應故。

Regarding the commentary's 'Tathatā is the sphere of action of the Buddhas': now, entering from this ninth bhūmi into the tenth bhūmi, why is it called entering into the sphere of action of the Tathāgata? Answer: Because the tenth bhūmi is equal to a Buddha, through the concordance of object and cognition.