Although the Theravadins/ Hinayanists have no the category of the "Buddha Nature", all true Mahayanists (with exception of some Yogacarins) insists that all the sentient beings possess the Buddha nature It is Tathagatagarbha, the Embryo of the Buddhahood in all beings. Buddha exclaims in Avatamsaka sutra: How wonderful, how surprising! All the beings are already endowed with the wisdom of the Buddha! They have already all Buddha qualities! How mysterious is it!
The Tiantai zong/Tiantai tsung of the Chinese Buddhism teaches that even "non continuums" (inanimate things) are also of the Buddha nature. And the task of the bodhisattva who says: "My great vow is to save/liberate all the beings" (i.e. to assist them in awakening of this inner and hidden Buddha nature which is the Clear Light) is just the same as the task of the Kabbalist in the raising up Holy Sparks.