give him enough rope and he'll hang himself

English

If one gives someone enough freedom of action, they may destroy themselves by foolish actions.

proverb

Italian: dare corda sufficiente per impiccarsi
Russian: заста́вь дурака́ бо́гу моли́ться, он и лоб расшибёт (zastávʹ duraká bógu molítʹsja, on i lob rasšibjót) (make a fool pray to the Lord, and he'll break his forehead), заста́вь дурака́ бо́гу моли́ться, он себе́ лоб расшибёт и други́м но́ги поотшиба́ет (zastávʹ duraká bógu molítʹsja, on sebé lob rasšibjót i drugím nógi pootšibájet) (make a fool pray to the Lord, and he'll break his forehead and hurt others' feet)