Shoyoroku - Case 85: The National Teacher's Gravestone [1]

Emperor Shukuso [2] asked Chu, the national teacher,
  "What would you wish me to do after a hundred years [3]?"
The national teacher said,
  "Make a seamless gravestone [4] for this old monk."
The emperor said,
  "I should like to ask you, master, for a design."
The national teacher remained silent for a long time. Then he said,
  "Did you understand?"
The emperor said,
  "I didn't understand anything."
The national teacher said, 
  "I have a Dharma successor, my disciple Tangen, who is well versed with
   this matter."
Afterwards the emperor called Tangen and asked him about the meaning of this.
Tangen responded: 
  "The south of the river, north of the lake:
   In between there's gold, which fills the whole land.
   Under the shadowless tree all people are in one boat;
   In the crystal palace there is no one who knows."

[1]]: see case 18 of Hekiganroku.
[2]: Historically speaking it was Emperor Daiso the oldest son and successor
     of Shukuso.
[3]: After your death.
[4]: An egg-formed gravestone which is made out of a single piece of stone.
     It was often made for deceased monks.