chest one's cards

verb2

1. •
   To hold one's hand close to one's chest so that other players cannot see the cards.

   • Another hand was dealt. Skookum chested his cards, looked down into them with one bright eye. The game went on. — 1930
2. •
   (figurative) To be careful and reticent about sharing information about one's resources and intentions.

   • The hardball line tells you to chest your cards (and maybe slip a couple up your sleeve). — 2013