Sakalya was the son of Sakala and he was also known as Vidagdha. As per Brihadaranyaka Upanishad, Sakalya lost his life in the debate against Yajnavalkya. This story is found in the third chapter of Brihadaranyaka Upanishad.
Once, King Janaka performed a very big yajna. At the end of the great ritual sacrifice, he announced in the assembly of scholars a gift of a thousand cows adorned with golden ornaments for the wisest among them.
When no one ventured forward, Yajnavalkya stepped forth and asked his disciple Somasrava to take the cattle home. The scholars turned against him and demanded that he answer their questions and prove his superior wisdom, to which Yajnavalkya readily consented.
A barrage of questions was unleashed by various scholars on Yajnavalkya, who responded to all of them with alacrity and authority.
Finally, Gargi, a woman scholar, confronted Yajnavalkya with some highly complex questions, which were handled competently by him. Gargi then admitted defeat and told the scholars that Yajnavalkya indeed was a deserving winner and that no one else had a chance of winning against him and suggested that they honor him accordingly.
Refusing to fall in line, Sakalya stood up and rudely directed a volley of questions towards Yajnavalkya regarding various deities. Yajnavalkya went on answering them patiently.
After a while, he warned Sakalya that with his mindless questioning he was inviting trouble. Refusing to heed the warning, Sakalya threw questions at him. Yajnavalkya once again patiently supplied all the answers. Eventually, he posed a single question to Sakalya and said that if he failed to answer it he would lose his head. Unable to answer the question, Sakalya fell dead. Besides, even the last rites for him could not be performed properly, since his body, while being taken by his students to his house, was snatched by robbers who mistook it for something else.
The episode is considered a warning to those who try to humiliate men of wisdom.