瑜伽師地論略纂 6.115

6.115

「三因緣故，於天趣中建立四眾」名：一、依地邊際建立二眾，謂四大王眾天、三十三天，居住別故；二、欲界邊際建立魔眾；三、語行邊際建立梵眾。

Regarding 'Due to three causal conditions, the four assemblies are established in the celestial destiny': first, establishing two assemblies based on the boundary of the earth, namely the assembly of the gods of the Four Great Kings and the gods of the Thirty-Three, because their dwelling places are distinct; second, establishing the assembly of Māra based on the boundary of the desire realm; third, establishing the assembly of Brahmā based on the boundary of the activity of speech.