The other boys who were being brought up and educated with St. Mungo by St. Serf are said to have been jealous of the love shown to him by their master, and to have done what they could to do him mischief. One story tells that a favourite tame robin of St. Serf was by accident killed by one or more of his youthful disciples, who laid the blame on Kentigern; whereon he took the bird in his hand, and having made over it the sign of the cross, its life was instantly restored, and it flew chirping or carolling to its master.