Quran 18:74 — The Cave (Al-Kahf)

So they went. When they met a young boy, he killed him. He said, "Why did you kill such an innocent soul, who did not kill another soul? You have committed something horrendous."

[18:73] He said, "I am sorry. Do not punish me for my forgetfulness; do not be too harsh with me."

[18:75] He said, "Did I not tell you that you cannot stand to be with me?"