keep quiet

verb2

1. •
   To remain silent.

   • Granny is asleep, so keep quiet while you play.
2. •
   To refrain from talking about something; to keep a secret.

   • Remember it's a surprise party, so keep quiet about it. — Okay. I'll keep it still
   • I'm quitting my job by the end of the month, but my boss doesn't know. Please keep it quiet.