speak for oneself

English

speak for oneself (third-person singular simple present speaks for oneself, present participle speaking for oneself, simple past spoke for oneself, past participle spoken for oneself)

(idiomatic, imperative) Expressing disagreement with an opinion expressed by another.
That idea makes no sense at all. – Speak for yourself! I think it's a great idea.
- 1838, Boz [pseudonym; Charles Dickens], “Looks after Oliver, and Proceeds with His Adventures”, in Oliver Twist; or, The Parish Boy’s Progress. […], volume II, London: Richard Bentley, […], →OCLC, page 138:
  “I’ll tell you what it is, gentlemen,” said he, “we’re all afraid.”¶ “Speak for yourself, sir,” said Mr. Giles, who was the palest of the party.
To have obvious implications; to require no explanation.
His fantastic record as a manager speaks for itself.

His actions speak for themselves.
- 1952 October, C. A. Johns, “One Hundred Years at Kings Cross—1”, in Railway Magazine, page 653:
  This relief to Kings Cross entailed an initial "stop-gap" service of 12 trains daily in each direction, increased to 34 each way from February 1 [1875], and to 43 each way by the following October—figures which speak for themselves.
Used other than figuratively or idiomatically: see speak,‎ for. To provide an opinion only on one's own behalf.
I'm here speaking for myself, not for my company.

In the imperative especially ("speak for yourself!"), this term suggests "I don't agree" or "believe what you like", hinting that the statement may be true for the speaker, but is not so for others.

expressing disagreement

to have obvious meaning