(as) steady as a rock British American simile
This simile uses rock in the sense of something that provides a certain support. It can be used to describe people and things
Used to describe things very stable, unmovable and well-built
This table is made of a special material, so it's as steady as a rock.
I want a door steady as a rock, unbroken by external forces
Used to describe someone absolutely and extensively steadfast, and trustworthy in difficult situations
After her husband's death, she become steady as a rock to shoulder the burden of providing for her family.
Whoever is selected to lead the business must be steady as a rock.
This simile, clearly alluding to a very large immobile rock, dates back to the mid-1800s. It is used to define either physical steadfastness or mental stability of behaviour. The former is intended by J. In Lady Flavia (1865), B. Harwood: "The hand holding the candle was like a rock steady." The latter appears in "You can count on John to run the office; he's like a rock steady."
To quit; to give up, stop doing something because you know that you cannot succeed; admit defeat
The team is not going to throw in the towel just because they lost one game.