大般涅槃經疏 31.8

31.8

「復有說言」下，第三破空是次第。言次第者，如簫管中及門向內。數人云：窓內見於外間之空，先於第一窓櫺中見，復於第二第三中見，此是次第。亦先牒、次破。

From "Again, there are those who say..." onward is the third, refuting [the view that] space is sequential. Saying "sequential" refers, for example, to [looking] through the pipes of a flute or inward through a door. The Abhidharma masters say: When looking from inside a window at the space outside, one first sees it through the first window lattice, and then sees it through the second and third; this is sequential. This also first cites it and then refutes it.