法苑珠林 70.57

70.57

問曰。若依毘曇說。彼四空遍在欲色二界之中。亦無定別。又彼無形。則無栖託。何故得說居止處耶。答曰。依如小乘。實當如是。若依大乘說。彼亦有微細色形。各有宮殿。別有四處。於三界中。別守一界。不雜餘二。是故說為四居止也。

Question: If one relies on the Abhidharma's explanation, those four formless states pervade the desire and form realms and also have no distinct locations; furthermore, being formless, they have no physical resting place. How then can they be called dwelling places? Answer: According to the Hīnayāna, it is indeed as you say. But according to the Mahāyāna, they also possess subtle physical forms and each has palaces; there are four distinct places. Within the tridhātu, each distinctively maintains one realm without mingling with the other two. Therefore, they are spoken of as four dwellings.