大般涅槃經義記 2.159

2.159

上來六句合為第一，自下第二約之顯化。亦說諸法無我、無常，明其昔日唯得說小；亦同女人始與兒蘇，是故言「亦」；亦可同前說消、不消，故云「亦說」。「若佛世尊先說常」下，彰其昔日不得說大。良以昔日凡情未遣故不得說，若為說大，便言此法與外道同，即便捨去。

The above six sentences together constitute the first part. From here below, the second part refers to it to reveal the transformation. "Also expounding all dharmas as non-self and impermanent" clarifies that in former days he was only able to expound the small; it is also like the woman initially giving her child ghee, hence it says "also"; it can also be like the earlier speaking of digesting and not digesting, hence saying "also expounded." From "If the Buddha, the World-Honoured One, had first expounded permanence" onward, it shows that in former days he was unable to expound the great. This was truly because in former days ordinary defilements had not yet been eliminated, and therefore he could not expound it; if he had expounded the great for them, they would have said this dharma is identical to non-Buddhists, and would immediately have abandoned it.