俱舍論記 13.155

13.155

「毘婆沙師至無無表色」者，又敘異解。為除惡戒故起尸羅，唯欲界中有諸惡戒，故於欲、色起善尸羅能對治彼。無色於欲具四種遠，故無色中無無表色。四遠如前廣心中釋。

Regarding "The Vaibhāṣikas... there is no unmanifest form": this recounts another explanation. Morality is undertaken to eliminate bad morality. Bad morality exists only in the Desire Realm; therefore, one undertakes good morality in the Desire and Form Realms to counteract it. The Formless [Realm] possesses four kinds of remoteness with respect to the Desire [Realm]; therefore, in the Formless [Realm] there is no unmanifest form. The four remotenesses are explained above in the section on the extensive mind.