法華義疏 8.38

8.38

「亦知眾生深心所行通達無礙」者，第六句，明善知根性也。既知理一而說有萬差者，以善達人根，隨其所宜故也。

Regarding 'He also knows the deep mental actions of sentient beings, penetrating them without obstruction': the sixth phrase, explaining skillful knowledge of faculties and dispositions. Knowing that the principle is one while the preachings are manifold is because he skillfully penetrates people's faculties in accordance with what is fitting.