金剛經纂要刊定記 4.38

4.38

非有想非無想者。第四天也。無麁想有細想，故是三有之頂，故云有頂。

Regarding "neither with perception nor without perception": this is the fourth heaven. Lacking coarse perception but having subtle perception, it is therefore the summit of the three realms of existence, hence called the 'Peak of Existence' (bhavāgra).