妙法蓮華經玄義 6.196

6.196

四空諸天，雖無欲色界等苦，如瘡、如癰、如癡、如箭入體，成就細煩惱。其中諸天，先世善根，可發關宜。聖人赴對應之，令獲冥顯兩益。

Although the gods of the four formless realms are free from the sufferings of the desire and form realms, they are like boils, like tumors, like blindness, like arrows entering the body, fully possessing subtle afflictions. If the gods therein have wholesome roots from prior lives that can be stimulated when conditions are fitting, the sages respond accordingly, causing them to obtain both hidden and manifest benefits.