Don't whistle before you are out of the woods proverb
Don't conclude a problem solved until it is completely resolved.
"Your heart operation was successful. You are no longer in any danger" - "There might be some complications. Don't whistle before you are out of the woods".
"The problem will be solved if he agrees to help us." - "Don't whistle before you are out of the woods".
Children or adults often say this phrase to get their friends to join in something, especially to jump into a swimming pool (pond, lake, etc.)
“Last one in is a rotten egg!” yelled Jane, jumping into the pool.