俱舍論記 28.98

28.98

「若爾此應至內等淨名」者，說一切有部以己宗難。若此定體遠離尋、伺即名內等淨者，此內等淨應無別體，如何許有十一實事？難訖述宗：是故應說此內等淨即是信根。謂若證得第二靜慮，於定地染亦可離中，有深信生名內等淨。得初定時，離散地染復雖生信，離定地染猶未生信，故於初定不立信支。後離初定染，復於定地信，故於二定立以信支。信是淨相，故立淨名。離外鼓動，定內等流，故名內等。淨而內等，故立內等淨名。

Regarding the passage "If so, this should... the name internal serene clarity": The Sarvāstivāda objects according to its own school: If the entity of this absorption being free from investigation and scrutiny is itself called internal serene clarity, then this internal serene clarity should have no distinct entity; how then can you accept eleven real entities? Having objected, he presents his own school: Therefore, it should be said that this internal serene clarity is precisely the faculty of faith. That is to say, when one attains the second absorption, when the defilement of the meditative stages can also be abandoned, profound faith arises, which is called internal serene clarity. When attaining the first absorption, although faith arises again upon abandoning the defilement of the scattered stages, faith has not yet arisen regarding abandoning the defilement of the meditative stages; therefore, in the first absorption the factor of faith is not established. Later, having abandoned the defilement of the first absorption, faith arises again regarding the meditative stages; therefore, in the second absorption it is established as the factor of faith. Faith has the characteristic of clarity; hence the name "clarity" is established. Free from external agitation, it flows equally within absorption; hence it is called "internal equality." Being clear and internally equal, the name "internal serene clarity" is established.