play one's cards close to one's chest, to

play one's cards close to one's chest

 and play one's cards close to one's vest; keep one's cards close to one's chest; keep one's cards close to one's vest
Fig. to keep to oneself or be very cautious in one's dealing with people. (As if one were playing cards and not permitting anyone to see any of the cards.) He is very cautious. He plays his cards close to his chest. You seem to be playing your cards close to your vest.
See also: card, chest, close, play

play one's cards close to one's chest, to

To be secretive. The analogy to holding one’s hand so that no one can see what cards are in it has been used since the mid-twentieth century. Agatha Christie had it in The Pale Horse (1961): “I couldn’t afford to give hints. You have to play these things close to your chest.”
See also: card, close, play