俱舍論記 9.166

9.166

「非一切經至此亦應爾」者，說一切有部救。非經皆了義，亦有隨勝說，如《象迹喻經》「云何內地界？謂髮、毛、爪等。」雖彼髮、毛、爪等，非無餘色、香、味、觸及餘三大等法，而就勝說。以髮、毛、爪等地界強故，故用髮、毛等釋內地界。此經所說無明等支，理亦應爾。雖彼非無餘色蘊等，而就勝說無明等名。

Regarding "not all sūtras [are definitive] ... here it should also be so": this is the Sarvāstivāda rescue. Not all sūtras are of definitive meaning; there are also those stated in terms of the predominant, just as the Simile of the Elephant's Footprint Sūtra says: "What is the internal earth element? It is hair, body hair, nails, and so forth." Although those hairs, body hair, nails, and so forth are not without the other matter, odor, taste, tangible, and the other three great elements, it is stated in terms of the predominant. Because the earth element is dominant in hair, body hair, nails, and so forth, hair, body hair, and so forth are used to explain the internal earth element. The members such as ignorance spoken of in this sūtra logically should also be like this. Although they are not without the rest of the form skandha and so on, the designation of "ignorance" and the rest is made according to what is predominant.