俱舍論疏 28.147

28.147

論「謂若證得至名內等淨」，此廣釋也。前初定中離其散地，今第二定離其定地。既自得二定離於初定，於其定地亦可離中有深信生，即所生信名內等淨。

On the Śāstra's phrase: "Namely, if one has attained [...] is called internal tranquility": this is an expanded explanation. Previously, in the first dhyāna, one was free from the uncollected plane (kāmadhātu); now, in the second dhyāna, one is free from that meditative plane. Once having personally attained the second dhyāna and being free from the first dhyāna, deep faith arises within that meditative plane that it is also capable of being abandoned; the faith that is produced is called internal tranquility.