The Buddhist tradition keeps one canonical prophecy of a coming teacher, and it appears where a first-time reader least expects it: at the end of a discourse about the rise and fall of societies.
The discourse
In the Cakkavatti-Sihanada Sutta (Digha Nikaya 26), the Buddha traces how a kingdom decays — not by cosmic decree but by a chain of ordinary failures: a ruler neglects the poor, poverty spreads, theft follows, then weapons, then killing, then lying, until human life and human trust have contracted to almost nothing. The discourse's low point is a brief "sword-interval" in which people see one another as animals to be hunted.
Then the turn: a remnant hides, survives, and resolves to do one good thing — to refrain from killing. From that single restored precept, generation by generation, life and virtue lengthen again. And at the far crest of that long recovery, the discourse says, there will arise in the world an Exalted One named Metteyya — a fully awakened Buddha, teaching the same Dhamma, lovely in its origin, lovely in its progress, lovely in its consummation, to a vast assembly.
What is easy to miss
Three things. First, Maitreya arrives at humanity's best hour, not its worst — the inversion of the Kalki pattern, where the redeemer comes at the bottom of the curve (compare the two). Second, the recovery in the discourse is entirely human work: no one descends to fix the sword-interval; people simply stop killing, and the world heals from that. Third, the discourse's own stated moral is not "wait for Maitreya" — it is the famous instruction that opens and closes it: be islands unto yourselves, refuges unto yourselves, with the Dhamma as your island.
Later centuries embroidered the figure — Maitreya cults, identified claimants, Theosophical "World Teachers" — but the canonical promise is spare, distant, and pointed firmly back at present conduct.
Reading further
The Dhammapada, which we keep whole in the Study Hall in Max Müller’s translation, is the compact form of the teaching Metteyya is promised to renew — read it verse by verse. For the discourse's central theme in other traditions, see work and duty and happiness and peace.
Related
The Kali Yuga passage · Ragnarok: the ending everyone forgets is a beginning · The Study Hall