Green’s Dictionary of Slang

(US) enough said, it is possible to infer all the facts from what has already been stated.

1841		Spirit of the Times (N.Y.) 30 Oct. 409: ‘N.S., nuf sed,’ and up went the soap.
1845		D. Corcoran Pickings from N.O. Picayune (1847) 64: Verbum sat sapienti, or, as the vulgar translation has it, N.S.