Proverbs 27:17 in the World English Bible
Iron sharpens iron; so a man sharpens his friend’s countenance.
Context
16 Whosoever hideth her hideth the wind, and the ointment of his right hand, which bewrayeth itself.
17 Iron sharpeneth iron; so a man sharpeneth the countenance of his friend.
18 Whoso keepeth the fig tree shall eat the fruit thereof: so he that waiteth on his master shall be honoured.