Where does this poem come from?

Pearl was very moved and said, "Your Majesty still remembers your brother!" Wu Ciyou didn't answer, two tearfully worshipped the imperial edict, and stood up, his robe sleeves were wet.

The next day, the two brothers finally broke up. On the Yellow River levee, the wind is cold and the dust is all over the sky. Their long braids fluttered behind their heads, sand waves swayed in the wind, thatched grass and slender willows danced in the wind, crying as if they were leaving someone. The two men held hands and looked at each other. After a long silence, Wu Ciyou suddenly sang:

You do what I do, and look to the west to lock Chang' an Road.

Wandering in the sand path of the ancient Yellow River, where will it float tonight?

The wind is blowing back and sighing, and I want to dance my sword to the sky.

Ok, don't watch the tragic actors of Gu Yan and Zhao, and don't go back to the west with a knife!

Try to hold a meeting in Mingde, and the long river will fall into the yen! ?

After singing, he smiled with tears: "Brother, let's get out of here!" "

Pearl burst into tears and fell to the ground. Wu Ciyou didn't dare to look at him again, so he turned over and got on the horse, and the three of them rode on the horse's head and didn't return. Pearl on the embankment? I hope that they will leave for western life until they can't see the figure. -Emperor Kangxi of February River