to be safe

(just) to be safe

As a precaution; in order to avoid potential problems, challenges, or risks. I'm sure we'd have enough time to catch our flight if we got the 11 AM shuttle to the airport, but let's take the 10 AM one just to be safe. I know you've got food with you, but it's going to be a really long trip, so I packed some extra snacks to be safe.
See also: safe
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

to be safe

to be cautious; to be careful; [to do something just] in case it is necessary; to be very well prepared. Just to be safe, you should take some extra water with you. Other people like to drive over the speed limit, but I prefer to be safe.
See also: safe
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
See also:
References in classic literature ?
what a wonderful thing to be safe! For two days I have been in terror.
"It's important to see that what people want is just the same - we all want to be loved and to be safe.