feather (one's) own nest

Translations
набивать себе карман
The corrupt official was found to be feathering his own nest with taxpayers' money.
Коррумпированного чиновника поймали на том, что он набивал себе карман за счет налогоплательщиков.
Definitions
To enrich oneself at every opportunity, often in a selfish or dishonest way, especially by taking advantage of one's position or resources.