The Long Āgama Sūtra 2.121

2.121

佛告阿難：「世有八眾。何謂八？一曰剎利眾，二曰婆羅門眾，三曰居士眾，四曰沙門眾，五曰四天王眾，六曰忉利天眾，七曰魔眾，八曰梵天眾。我自憶念：『昔者，往來與剎利眾坐起言語，不可稱數，以精進定力，在所能現。彼有好色，我色勝彼；彼有妙聲，我聲勝彼；彼辭我退，我不辭彼；彼所能說，我亦能說；彼所不能，我亦能說。』阿難！我廣為說法，示教利喜已，即於彼沒，彼不知我是天、是人？如是至梵天眾，往返無數，廣為說法，而莫知我誰？」

The Buddha told Ānanda, “The world has eight assemblies. What are the eight? First is the warrior assembly. Second is the priestly assembly. Third is the householder assembly. Fourth is the ascetic assembly. Fifth is the assembly of the four god kings. Sixth is the assembly of the Trāyastriṃśa gods. Seventh is the Māra assembly. Eighth is the assembly of Brahma gods.

“I remember this about myself: Once, I was reborn with an assembly of warriors, sitting, rising, and speaking with them. I can’t say how many times. With effort and the power of samādhi, I was able to appear among them. They had excellent forms, and my form was better than theirs. They had wonderful voices, and my voice was better than theirs. They would concede to me and withdraw, but I didn’t concede to them. What they could explain, I could explain, too. I could also explain what they couldn’t.

“Ānanda, I broadly taught the Dharma, teaching, instructing, profiting, and delighting them, and then I would disappear from that place. They didn’t know whether I was a god or a human. So it was up to the assembly of Brahma gods. I couldn’t count how many times I went there. I broadly taught them the Dharma, but they didn’t know what I was.”