Narrated Ibn 'Abbas:
that Ubayy bin Ka'b narrated that the Prophet (ﷺ) said: "The boy that Al-Khidr killed was destined to be a disbeliever the day he was created.'" (ID)
English reference (ID): Vol. 5, Book 44, Hadith 3150 (ID)
Arabic reference (ID): Book 47, Hadith 3443 (ID)