What is the name of the poem that Mr Zhu sang in White Deer Plain? What is the moral of this poem sung by Mr. Zhu?

The poem sung by Mr. Zhu is Qu/Ji Yuan Er Shi An, and the original text is:

The rain in the early morning moistened the dust of the land, the inn of the inn, the branches and leaves of the inn, and a new leaf Sincerely advise friends to drink a glass of wine, and it is difficult to meet their loved ones when they go out to Yang Guan in the west.

Mr. Zhu told Bai Jiaxuan that it was sung to him when he was studying abroad, and told this gentleman that he had to go through hardships before he could reach the great realm. But when he was fearless, now he understood Fang Sheng's intention. This poem describes a feeling of parting. Zhu Xian was afraid that he could not pass this test, so he began to sing this poem with a farewell feeling.