Akademik

О-70
ПО ОДЁЖКЕ (ПО ПЛАТЬЮ) ВСТРЕЧАЮТ, ПО УМУ ПРОВОЖАЮТ (saying often only the first half of the saying is used) the first thing one notices when meeting s.o. is his outer appearance, but once one gets to know him it is his intelligence, personality etc that matters: - clothes count only for first impressions looks (appearances) matter only upon first meeting you are judged by appearances at first but by your mind later on (when only the first half is used) people judge you by appearances people treat you according to your clothes.
(Виктория:) По одежке, значит, встречаете? (Калошин.) А ты думала? На этой работе глаз - первое дело... (Виктория:) А что - одбжка? Есть большие люди, а одеваются скромно... (Вампилов 1). (V.:) You mean you treat all guests according to their clothes? (K.:) What do you think? In this job you don't get far without sharp eyes.... (V.:) What do clothes tell you? Plenty of important people dress modestly... (1a).

Большой русско-английский фразеологический словарь. — М.: ACT-ПРЕСС КНИГА. . 2004.