From Longman Dictionary of Contemporary Englishfeather your nestfeather your nestRICHto get money by dishonest methods → feather
Examples from the Corpus
feather your nest• But they were all like that, more or less, all interested in feathering their nests at his expense.• Wetherby may have decided to feather his nest by blackmail.• The Bolshoi is full of indolent time-servers, more interested in feathering their nests than in Swan Lake.• So long as they were in favour, they were free to feather their nests, which Andrei did as industriously as anyone else. 