enough is enough

From its older use as an expression of content or satisfaction (cf. enough is as good as a feast), this is now frequently used as a reprimand, warning someone off from persisting in an inappropriate or excessive course of action.

Sens enough is enough (sayd I) here maie we With that one word take end good.
[1546 J. Heywood Dialogue of Proverbs ii. xi. M1]

‘I will descend for no more,’ said the Moor, doggedly; ‘enough is enough for a reasonable man—more is superfluous.’
[1832 W. Irving Alhambra II. 40]

I realize all its merits just as well as you do. But enough is enough.
[1915 T. Dreiser Titan (ed. 3) xlvii. 404]

We all enjoyed your encouraging letter—‘Dear Sir, The bank looks forward to a return to the traditional arrangement whereby you bank with us, rather than vice-versa. Enough is enough.’
[2002 Times 10 Aug. 23]

Related to: content and discontent; moderation

Bibliography of major proverb collections and works cited from modern editions is available here.

One should be satisfied; stop, there should be no more. For example, No more speeches--enough is enough, or as Robert Southey put it (The Doctor, 1834): "As for money, enough is enough; no man can enjoy more." This expression already appeared in John Heywood's proverb collection of 1546 and is often used as an interjection (first example).