瑜伽論記 4.30

4.30

等至中有六門，八勝處十遍因解，解脫已略解訖，更不釋之。決擇等中，釋四無色不異解脫，故亦不解。

In samāpatti there are six divisions. The eight bases of mastery and the ten totalities are explained by means of [their] causes; since liberations have already been briefly explained, they are not explained again. In the Viniścaya and elsewhere, the four formless [attainments] are explained as not different from the liberations, hence they are also not explained here.