Don't judge a horse by its saddle, and don't judge a person by his cloth.

解释 ( paraphrase )
一匹马是不是好，不在乎它的鞍怎样；一个人是不是好，不在乎他穿的衣衫怎样。
这条谚语告诉我们：对待事物或评价一个人，不能光看表面，而要看重他的实质。

This proverb tells us not to judge a person or thing simply by outward appearances.

同义词 ( synonym )
画虎画皮难画骨，知人知面不知心。

造句 ( example )
正所谓“马好不在鞍，人好不在衫”，别看他穿着简陋，可是咱们附近有名的善人呢。