(give someone) an inch and (they'll) take a mile

Translations
дай (кому-то) палец, (он) всю руку откусит
If you give him an inch, he'll take a mile.
Если дать ему палец, он всю руку откусит.
Definitions
This phrase means that if you give someone a small amount of freedom or help, they may take advantage of it and demand or take much more than you intended to give. It suggests that some people are likely to exploit generosity or leniency.
Words
give

verb
дать
someone

pronoun
кому-либо
an

article or possessive pronoun
один
inch

noun
дюйм
and

conjunction
и
they

pronoun
они
will

functional word
будут
take

verb
взять
a

article or possessive pronoun
один
mile

noun
миля