摩訶止觀 6.18

6.18

次、破無色界九品者：若欲滅有對等三種之色，是時破事障，發未到；破性障，入空處。空處定亦具愛、慢、癡，還用四觀方便勝進，成事理無生。若不去，更修相續、相待，亦如是。八品及癡、慢等，亦如是。

Next, breaking the nine grades of the formless realm: if one wishes to annihilate the three kinds of form such as that of resistance, at that time breaking the obstacles of phenomenal activity brings forth the threshold stage; breaking the obstacles of intrinsic nature enters the stage of boundless space. Concentration on boundless space also possesses attachment, arrogance, and delusion; one again uses the four contemplations, with skillful means of superior advancement, to accomplish the non-arising of phenomenal activity and principle. If they are not removed, one further cultivates [contemplation of] continuity and relativity in the same way. The eight grades, as well as delusion and arrogance, are likewise treated.