首楞嚴義疏注經 1.250

1.250

前云赴請，此云乞食者，乞食乃是常儀，泛舉為喻。又前雖赴請，未必僧盡，餘人乞食，故舉此也。宿，預也。

Previously it mentioned attending an invitation, whereas here it mentions begging for food; begging for food is the standard conduct, cited generally as an analogy. Furthermore, although they previously attended an invitation, the Saṅgha was not necessarily all there, and the remaining individuals begged for food; hence this is mentioned. *Su* (宿) means in advance.