Proverbs 27:17
"Iron sharpeneth iron; so a man sharpeneth the countenance of his friend."
Cross References (ranked by relevance)
And let us consider one another to provoke unto love and to good works:
Ointment and perfume rejoice the heart: so doth the sweetness of a man’s friend by hearty counsel.
And Jonathan Saul’s son arose, and went to David into the wood, and strengthened his hand in God.
Thou therefore endure hardness, as a good soldier of Jesus Christ.
My brethren, count it all joy when ye fall into divers temptations;
Be not thou therefore ashamed of the testimony of our Lord, nor of me his prisoner: but be thou partaker of the afflictions of the gospel according to the power of God;
That no man should be moved by these afflictions: for yourselves know that we are appointed thereunto.
For the which cause I also suffer these things: nevertheless I am not ashamed: for I know whom I have believed, and am persuaded that he is able to keep that which I have committed unto him against that day.
Whosoever he be that doth rebel against thy commandment, and will not hearken unto thy words in all that thou commandest him, he shall be put to death: only be strong and of a good courage.