handsome is as handsome does
How one acts is more important than how one looks. For example, He may be homely, but he's the kindest man I've ever met—handsome is as handsome does. This expression already appeared in John Ray's 1670 collection of proverbs.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.