Vali killed the buffale demon Dundhubi and flung him away. The dead body ended up in the hermitage of sage Matanga. He cursed Vali, should he or any of his friends ever get too close to him, they would become a stone
For the story about Dundhubi visit
http://hindumythologyforgennext.blogspot.com/2016/07/tara-queen-of-kishkinda-part-1-of-2.html