瑜伽論記 2.63

2.63

下辨無色界受，極寂靜解脫之樂者，空處離色想滅有對想息種種相，識處離空想緣彼空處無邊之識，無所有處離識無邊想，推求識處上境界無少所得除無所有，非想非非想處超無所有想緣無所有處上境界，唯得無所有極細心心所，由此想故名極寂靜，隨離下障名解脫樂，對法亦言：寂靜異熟，由彼界中有滅定故；心行細故；無業色故；果長時故，名為寂靜解脫之樂。此及第四定受彼身心安適名樂，體非樂受。

Below, in distinguishing the experience of the formless realm, regarding 'the pleasure of the most tranquil liberation': the [stage of] limitless space is free from perceptions of form, destroys perceptions of sensory resistance, and stills manifold characteristics; the [stage of] limitless consciousness is free from perceptions of space and takes as its object the limitless consciousness of that stage of space; the [stage of] nothingness is free from the perception of limitless consciousness, seeking higher realms beyond the stage of consciousness and finding nothing whatsoever to be apprehended apart from nothingness; the [stage of] neither-perception-nor-non-perception transcends the perception of nothingness and takes as its object higher realms beyond the stage of nothingness, apprehending only extremely subtle mind and mental factors of nothingness. Because of such perceptions, it is called 'most tranquil'. According as it is free from lower obstructions, it is called the 'pleasure of liberation'. The Abhidharma also states: tranquil vipāka is called the 'pleasure of tranquil liberation' because there is the attainment of cessation in that realm, because mental activities are subtle, because there is no karmic form, and because the fruition lasts for a long time. In this [formless realm] and in the fourth dhyāna, experiencing that physical and mental comfort is called 'pleasure'; its essence is not pleasurable feeling.