《太平广记·卷二十九·神仙二十九》
玄宗笑道： 我昨天夜里梦见仙人奏乐，曲名叫《紫云曲》，他们就把曲子传授给我。我怕忘了它的节奏，因此默默地在心里练习，所以顾不上听二位国相奏事。 
玄宗笑曰： 我昨夕梦仙人奏乐曰《紫云曲》，因以授我，我失其节奏，由是嘿而习之，故不暇听二相奏事。 
Xuanzong smiled and said: “Last night, I had a dream where an immortal played music for me. The song was called “Purple Cloud Melody,” and they passed the melody on to me. I was afraid that I would forget its rhythm, so I practiced it silently in my heart. That’s why I didn’t have the time to listen to the two national ministers’ report.”