This psalm is said in three parts: 'To the conductor, on the white lilies, a wise song of friendship.' This corresponds to the three sons of Korah. And because there were three of them, it says 'friendship' three times. The Holy One, blessed be He, said, 'Each and every one of them is a friend of Mine.' How do we know that even Moses, Aaron, and all the great ones were not as eager to hear the song of the sons of Korah, as it says (Psalm 45:1), 'To the conductor over the white lilies, a wise song of friendship'? This teaches us to sing to the Holy One, blessed be He, as it says (Isaiah 54:13), 'And all your children shall be taught of the Lord.'"