noun
motto
MAH-toh/ˈmɑːtəʊ/
A short phrase expressing a guiding principle, aim, or ideal.
The hiker follows the motto 'Keep going' while persisting uphill.

Etymology
From muttum, “a grunt” or “a word,” motto came to mean a short phrase explaining an emblem. Such a phrase could then express a principle adopted as a rule of conduct.
In context
including those whose motto might be "don't do evil," to pay taxes