...[A]ccording to Buddhism in the Tibetan tradition,....

“ ...[A]ccording to Buddhism in the Tibetan tradition, a being that achieves Buddhahood, although freed from Samsara,the 'wheel of suffering', as the phenomenon of existence is known, will continue to return to work for the benefit of all other sentient beings until such time as each one is similarly liberated. ”

Dalai Lama XIV

From : Freedom in Exile: The Autobiography of the Dalai Lama