《论衡·卷四·书虚篇》
传书上说：舜葬在苍梧，象为他耕地；禹葬在会稽，鸟为他耕田。
传书言：舜葬於苍梧，象为之耕；禹葬会稽，鸟为之田。
According to the book of historical records: Emperor Shun was buried in Cangwu, and elephants ploughed the land for him; Emperor Yu was buried in Kuaiji, and birds ploughed the land for him.