首楞嚴義疏注經 6.247

6.247

優波離因持清禁，由是執身身得自在，次第執心心得通達，然後身心一切無礙。今揀持犯細行唯檢於身，身若不生將何檢束？故於法法不能圓遍。

Upāli, by observing pure prohibitions, thereby controlled the body and attained bodily mastery; gradually controlling the mind, the mind attained comprehension; thereafter, body and mind were free of all hindrances. Here it is selected out: the fine details of keeping and breaking precepts only regulate the body; if the body does not arise, what will be regulated? Therefore, with respect to phenomenon after phenomenon, it cannot be perfectly pervasive.