The Buddha taught in the Uposatha Sutta,

"And furthermore, just as the ocean is the abode of such mighty beings as whales, whale-eaters, and whale-eater-eaters; asuras, nagas, and gandhabbas, and there are in the ocean beings one hundred leagues long, two hundred... three hundred... four hundred... five hundred leagues long; in the same way, this Doctrine and Discipline is the abode of such mighty beings as stream-winners and those practicing to realize the fruit of stream-entry; once-returners and those practicing to realize the fruit of once-returning; non-returners and those practicing to realize the fruit of non-returning; Arahants and those practicing for Arahantship. The fact that this Doctrine and Discipline is the abode of such mighty beings as stream-winners and those practicing to realize the fruit of stream-entry; once-returners and those practicing to realize the fruit of once-returning; non-returners and those practicing to realize the fruit of non-returning; Arahants and those practicing for Arahantship: This is the eighth amazing and astounding fact about this Doctrine and Discipline that, as they see it again and again, has the monks greatly pleased with the Doctrine and Discipline."