STEADINESS
(as) steady as a rock
very steady and unmovable; very stable.His hand was steady as a rock as he pulled the trigger of the revolver.You must remain as steady as a rock when you are arguing with your supervisor.
stand one's ground and hold one's ground
to stand up for one's rights; to resist an attack.The lawyer tried to confuse me when I was giving testimony, but I managed to stand my ground.Some people were trying to crowd us off the beach, but we held our ground.