Draumr Þorsteins Síðu-Hallssonar (The Dream of Þorsteinn Son of Síðu-Hallr) is a very short þáttr which tells how Þorsteinn was visited in dreams by three women who warned him that he would soon be murdered. It was written at the end of the 13th century.
As Þorsteinn was sleeping, three women appeared to him. They warned him that his slave Gilli was willing to avenge for he had been castrated on Þorsteinn’s orders. They advised him to kill him but the slave was nowhere to be found. They came back the next two nights and again forecast his death, as well as his son's. The night after, Gilli cut Þorsteinn's throat as he was asleep. He was caught by Þorstein's servants, tortured to death and his body was thrown into a fen.
The three dream-women (draumkonur) referred to in this tale are very likely to be fylgjur.