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.'" (PT)
English reference (PT): Vol. 5, Book 44, Hadith 3150 (PT)
Arabic reference (PT): Book 47, Hadith 3443 (PT)