Brahmajalasutta 2.35.2

2.35.2

Ye hi keci, bhikkhave, samaṇā vā brāhmaṇā vā pubbantakappikā pubbantānudiṭṭhino pubbantamārabbha anekavihitāni adhimuttipadāni abhivadanti, sabbe te imeheva aṭṭhārasahi vatthūhi, etesaṃ vā aññatarena, natthi ito bahiddhā.

Any ascetics and brahmins who speculate and theorize about the first beginning do so on one or other of these eighteen grounds. Outside of this there is none.