119Bonwick, James. Irish Druids and Old Irish Religions. London: Griffith, Farran & Co., 1894. Rpt. New York: Arno Press, 1976, p. 57.

From a 1927 journal article, here's another account of the stone's prophetic powers:
"Conn Ced-Chathach, it is told, ascended the hill of Temair at sunrise, and stood on a stone at its top. To his surprise ‘The stone screamed under his feet so as that it was heard all over Temair.’ One of the druids in due course explained : ‘Fal is the name of the stone. It was out of the Island of Foal it was brought. It was in Temair of the Land of Fal it was set up. In the land of Tailltin it shall abide for ever; and it is that land that shall be the sporting fair-green as long as there shall be sovereignty in Ternair.’ Then appeared Scal (the Spectre) who revealed to Conn his coming sovereignty at Temair, and the sovereignty of each and all of Conn's descendants. They entered the house in Tara, and saw a young woman there with a diadem of gold upon her head. ‘And the maiden who was in the house before them was the sovereignty of Erinn for ever.’" (Dalton, John. "The Coming of the Ui-Briuin." Journal of the Breifny Antiquarian and Historical Society, vol. III, no. 1, 1927, p. 138. Read online here.)

Mcalister quotes a later version of the Book of Invasions's account of the stone's voice: "'There was a demon in the stone...who uttered the cry, down til the birth of Christ; but thereafter it was silent, for the power of demons was broken when Christ was born.'" (Macalister, Robert Alexander Stewart. Tara, a Pagan Sanctuary of Ancient Ireland, New York: C. Scribner's Sons, 1931, p. 30.)