be calm

See: repose, rest
References in classic literature ?
He stood before her, pale, his lower jaw quivering, and besought her to be calm, not knowing how or why.
I will be calm and focused on my players and I will be exactly the same if I am at Chelsea, Accrington (Stanley) or Aldershot.
As a manager you have to be calm and leave the fans to dream - because there are still a lot of games to go.