Discretion is the better part of valour

Discretion is the better part of valour.  (British & Australian literary) also Discretion is the better part of valor. (American & Australian literary)

something that you say which means that it is better to be careful and think before you act than it is to be brave and take risks She decided not to voice her opposition to the Chairman's remarks. Perhaps discretion was the better part of valour.

See also: better, discretion, part