A proverb meaning 'a samurai does not go back on his word' — expressing that one should keep promises and stand by one's words.
彼は約束を破らない。まさに『武士に二言はない』だ。
He never breaks his promises — truly 'a samurai does not go back on his word.'
あの会社は契約に忠実で、武士に二言はないという感じだ。
That company is faithful to contracts; it feels like 'a samurai does not go back on his word.'