This tradition has been narrated by the game authority (Yazid b. Hurmus) through a different chain of transmitters with the following difference in the elucidation of one of the points raised by Najda in his letter to Ibn Abas:
The Messenger of Allah ( صلی اللہ علیہ وسلم ) used not to kill the children, so thou shouldst not kill them unless you could know what Khadir had known about the child he killed, or you could distinguish between a child who would grow up to he a believer (and a child who would grow up to be a non-believer), so that you killed the (prospective) non-believer and left the (prospective) believer aside.