Admonitory

The schoolboy left an admonitory message on the bathroom wall.

Source: wiktionary

He wagged an admonitory finger at the culprit.

Source: wiktionary

Wherefore the naturall measure wherby to iudge our doings, is the sentence of reason, determining and setting downe what is good to be done. Which sentence is either mandatory, shewing what must be done; or else permissiue, declaring onely what may be done; or thirdly admonitorie, opening what is the most conuenient for vs to doe.

Source: wiktionary

Mere descriptions of virtue or vice do not strike us, so strongly, as the visible representations of them. Richard the Third’s dream, Lady Macbeth’s soliloquy in her sleep, the Dagger Scene in the same Play, Cardinal Beaufort’s last moments, with many other passages in our Author, of the same admonitory kind, avail us more than whole volumes of Tully’s Offices, or Seneca’s Morals.

Source: wiktionary