大方廣佛華嚴經隨疏演義鈔 4.37

4.37

疏「又亦攝」下，上辯潛入，佛入生身，生不知故。今明攝他，正攝他時不礙入他，故稱無礙。

Below where the commentary states "and also gathering in": above, it discussed covert entry, which is the Buddha entering the bodies of sentient beings without sentient beings knowing. Now it explains gathering in others: at the very moment of gathering in others, it does not impede entering others; therefore it is called unimpeded.