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".
Use ink or some type of digital scanner to record one's fingerprints
The police wants to roll all people's finger prints in the office.