俱舍論頌疏論本 3.35

3.35

中捨二無別者，中謂非悅非不悅，即是不苦不樂受，此處中受名為捨根。二者，謂身、心二也。身即五識，心是意識，捨在身心，同無分別，任運而生，故雖通二，立一捨根。又論云：「在心苦樂，多分別生。在身不然，隨境力故。阿羅漢等，亦如是生。故此立根，身心各別。」解云：在心苦樂者，意地受也。苦樂在心，分別起故，苦名為憂，樂名為喜。樂受在第三禪，即無分別。為簡此故，故言多分別生也。苦、樂二受在五識身，無分別故，名為不然。謂五識身隨境力故，名無分別。阿羅漢等，舉聖同凡。故此苦樂在五識身，名苦名樂。在第六識，名喜名憂也。

"The neutral [feeling] of equanimity is indistinguishable in both" means: "neutral" refers to that which is neither pleasant nor unpleasant—that is, feeling that is neither suffering nor pleasure. Feeling abiding in this neutral state is called the equanimity faculty (upekṣendriya). "Both" refers to both body and mind. The body is the five consciousnesses, and the mind is mental consciousness. When equanimity is in the body or mind, it is alike without conceptual discrimination and arises spontaneously; therefore, although it extends to both, it is established as a single equanimity faculty. Furthermore, the treatise states: "Suffering and pleasure in the mind mostly arise through conceptual discrimination. In the body it is not so, because it follows the force of the object. For arhats and others, it also arises in this manner. Therefore, these are established as faculties with body and mind kept distinct." The explanation states: "Suffering and pleasure in the mind" refers to feeling of the mental ground. Because suffering and pleasure in the mind arise through conceptual discrimination, suffering is called grief and pleasure is called gladness. When the feeling of pleasure is in the third dhyāna, it is free from conceptual discrimination. To exclude this, it is said that they "mostly arise through conceptual discrimination". Because the two feelings of suffering and pleasure in the physical body of the five consciousnesses are free from conceptual discrimination, it is said that "it is not so". This means that because the physical body of the five consciousnesses follows the force of the object, it is called free from conceptual discrimination. "For arhats and others" adduces the noble ones to show they are identical with ordinary beings. Therefore, when these [feelings of] suffering and pleasure are in the physical body of the five consciousnesses, they are called suffering and pleasure; when in the sixth consciousness, they are called gladness and grief.