俱舍論記 4.20

4.20

「前說色界至故不別說」者，此即第二便明上界。類釋色界。前文具說於色界中香、味竝無，故彼無聲，有六、七、八。有聲有七、八、九俱生，此可准知，故於頌文不別說也。

Regarding "Previously it was stated that in the form realm [...] therefore it is not separately stated": this is the second part, which in turn clarifies the higher realm. It explains the form realm by analogy. The previous text fully explained that in the form realm, odor and taste are both absent; therefore where sound is absent there are six, seven, or eight, and where sound is present there are seven, eight, or nine arising simultaneously. This can be understood by analogy, and therefore it is not separately stated in the verse.