All conditioned things are impermanent (Skt. anitya) … Impermanence and no-self are th[e unified message from the Buddha].
Dōgen presents impermanence as the first of the four Dharma seals and insists it is inseparable from no-self, duḥkha, and nirvāṇa — a unified soteriological teaching rather than an isolated doctrine.
, Shōbōgenzō Zuimonki, 1234thesis