馬の耳に念仏 (Uma no mimi ni nenbutsu)

Literally: A Buddhist prayer in a horse's ear

Example: “弟に勉強しろと言っても馬の耳に念仏だ。” — Telling my brother to study is like talking to a brick wall.

English equivalent: Like talking to a brick wall

Origin: Traces back, through a plausible but not entirely certain chain, to a line by the Tang-dynasty Chinese poet Li Bai, who wrote of words passing over an indifferent listener "as the east wind blows past a horse's ear." The Edo-period Japanese version originally ran simply "uma ni nenbutsu" — a Buddhist prayer recited to a horse, equally useless work — but is thought to have gradually merged with an older, separate expression, "uma no mimi ni kaze" (wind in a horse's ear), a closer cousin of Li Bai's original line, eventually settling into the combined modern form. A specific documented use appears in the 1865 kabuki and puppet-theater play Tsuru Chitose Soga Kadomatsu, treating the phrase as an established, recognizable insult for hopelessly wasted advice by that date.