 To decide who would become the monarch, six of them decided on a test, with Otanes abstaining, as he had no interest in being king.They were to gather outside the palace, mounted on their horses at sunrise, and the man whose horse neighed first in recognition of the rising sun would become king.According to Herodotus, Darius had a slave, Oebares, who rubbed his hand over the genitals of a mare that Darius's horse favored.