It’s a rule of firearm safety. Unfortunately, in the US you don’t need to follow those or many rules for ownership.

4 rules of firearm safety:

1-treat every firearm as if it’s loaded

2-don’t point your firearm at anything you don’t intend to destroy

3-keep your finger off the trigger until ready to fire

4-know your target, backstop, and beyond

Bonus 5- don’t do anything stupid