The Long Āgama Sūtra 24.21

24.21

「長者子！彼四天王報比丘言：『我不知四大由何永滅？我上有天，名曰忉利，微妙第一，有大智慧，彼天能知四大由何而滅。』彼比丘聞已，即倐趣天道，往詣忉利天上，問諸天言：『此身四大，地、水、火、風，何由永滅？』彼忉利天報比丘言：『我不知四大何由滅，上更有天，名焰摩，微妙第一，有大智慧，彼天能知。』即往就問，又言不知。

“Prominent man’s son, those four god kings replied to that monk, ‘We don’t know. How are the four elements made to cease forever? There’s a heaven above us called the Trāyastriṃśa, which is sublime and supreme. The gods there have great wisdom. Perhaps they know how to make the four elements cease?’

“Hearing this, the monk then instantly headed for the heavenly road. He went up to the Trāyastriṃśa Heaven and asked those gods, ‘How are the four elements of this body made to cease forever, which are earth, water, fire, and air?’

Those Trāyastriṃśa gods replied to the monk, ‘We don’t know. How are the four elements made to cease forever? There’s a heaven above us called Yama which is sublime and supreme. Having great wisdom, the gods there may know.’ He went there and asked, but they said they didn’t know.