The Questions of the Naga King Sagara
The sūtra known as The Questions of the Nāga King Sāgara (Skt. Sāgaranāgarājaparipṛcchā, Tib. ཀླུའི་རྒྱལ་པོ་རྒྱ་མཚོས་ཞུས་པ་, lü gyalpo gyatsö shyüpa, Wyl. klu’i rgyal po rgya mtshos zhus pa) is found in the General Sūtra (mdo sde) section of the Tibetan Kangyur (Toh 155).
In this very brief sūtra, the Buddha explains the four seals of dharma to a nāga king and assembly of monks.