to rest on ones laurels

from The Collaborative International Dictionary of English v.0.48
laurels \lau"rels\, n. pl.
   An honor or honors conferred for some notable achievement.
   [PJC]

   {to rest on one's laurels} [fig.] to be content with one's
      past achievements and not strive to continue to excel; as,
      he didn't rest on his laurels after receiving the Nobel
      Prize, but went on to made even more significant
      discoveries.
      [PJC]
antiflux / dictionary / to rest on ones laurels
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