Proverbs 27:17-21

Iron sharpeneth iron; So a man sharpeneth the countenance of his friend. Whoso keepeth the fig-tree shall eat the fruit thereof; And he that regardeth his master shall be honored. As in water face answereth to face, So the heart of man to man. Sheol and Abaddon are never satisfied; And the eyes of man are never satisfied. The refining pot is for silver, and the furnace for gold; And a man is tried by his praise.