The boy whom al-Khidr had killed was created an infidel. Had he lived, he would have moved his parents to rebellion and unbelief.
Sunan Abi Dawud Book 42, Hadith 110
← Previous Hadith I was with ‘Umar b. al-Khattab when he transmitted this tradition. The tradition of Malik is more perfect.

Sunan Abi Dawud Book 42, Hadith 109 Next Hadith → I heard the Messenger of Allah (May peace be upon him) explaining the verse “As for the youth his parents were people of Faith,” he was created infidel the day when he was created.

Sunan Abi Dawud Book 42, Hadith 111