A Torah scholar (talmid chacham) whose inner self is not as his external self is no Torah scholar
Talmud, Yuma 72b
Said the chassid Rabbi Yehoshua Eliyahu of Harki:
Why does the Talmud say that one must make his “inner self as his external self” and not the other way around? Because to make your external self as your inner self is a relatively simple task: you need only behave in a manner that is in keeping with your present moral and spiritual state. The challenge is to act more righteously than you truly are, and then, so as not to be a hypocrite, G-d forbid, make your inner self consistent with your external behavior.
Adapted from the teachings of the Lubavitcher Rebbe by Yanki Tauber