俱舍論疏 8.108

8.108

論「下三無色至是名為七」，指經釋後三識住也，即是空無邊處五，識無邊處六，無所有處七。「是名為七」者，結七識住也。

The verse commentary states: "The lower three formless realms [...] these are called the seven." This refers to the sūtra to explain the latter three stations of consciousness; namely, the stage of boundless space is the fifth, the stage of boundless consciousness is the sixth, and the stage of nothingness is the seventh. "These are called the seven" concludes the seven stations of consciousness.