SB 10.58.33
na tam sekur nrpa vodhum
ajitva sapta-go-vrsan
tiksna-srngan su-durdharsan
virya-gandhasahan khalan
Translation:
The kings who came as suitors were not allowed to marry her unless they could subdue seven sharp-horned bulls. These bulls were extremely vicious and uncontrollable, and they could not tolerate even the smell of warriors.