The Wisdom of Confucius (Lun Yu) 孔子的偉大智慧 : 論語

“益者三友，損者三友。友直，友諒，友多聞，益矣。友便辟，友善柔，有便佞，損矣。

”You should choose friends who are righteous, honest and knowledgeable;But you should avoid making friends with those who like flattering you but slandering you at your back, those which always like praising everyone in a very artful way.