彰所知論 2.30

2.30

四無色者，修加行時，思無邊空及無邊識、無所有故，以正定時除色依餘四蘊。第四名者，由想昧劣，謂無明勝，得非想名；有昧劣想，名非非想。如是次第，空無邊處、識無邊處、無所有處、非想非非想處，名四無色。若加滅盡定，亦名九次第定。

The four formless states: when cultivating the preparatory practice, because one contemplates infinite space, infinite consciousness, and nothingness, at the time of correct concentration one eliminates form and relies on the remaining four aggregates. The name of the fourth: because its perception is faint and obscure, meaning ignorance is predominant, it receives the name 'neither perception'; yet having faint and obscure perception, it is called 'nor non-perception'. In this order: the base of infinite space, the base of infinite consciousness, the base of nothingness, and the base of neither perception nor non-perception are called the four formless states. If cessation attainment is added, they are also called the nine progressive attainments.