bite (the) hand that feeds (someone)

Translations
кусать руку, которая кормит
He bit the hand that feeds him by criticizing the company publicly.
Он укусил руку, которая его кормит, публично критикуя компанию.
Definitions
To act against or harm someone who is helping or supporting you, often in a way that is ungrateful or disloyal.
Words
hand

noun
рука
bite

verb
кусать
feed

verb
кормить