The words are
王维's quatrain for a friend leaving for the Western Regions:
渭城朝雨浥轻尘,
客舍青青柳色新。
劝君更尽一杯酒,
西出阳关无故人。 'Morning rain in Weicheng has settled the light dust; by the inn the willows are fresh and green. Drink one more cup of wine, my friend: west of Yang Pass you will have no old friends.' Sung three times over with added words, it became the classic song of parting.