﴿ فَٱنطَلَقَا حَتَّىٰٓ إِذَا لَقِيَا غُلَٰمًۭا فَقَتَلَهُۥ قَالَ أَقَتَلْتَ نَفْسًۭا زَكِيَّةًۢ بِغَيْرِ نَفْسٍۢ لَّقَدْ جِئْتَ شَيْـًۭٔا نُّكْرًۭا ﴾

“And so the two went on, till, when they met a young man, [the sage] slew him -(whereupon Moses] exclaimed: "Hast thou slain an innocent human being without [his having taken] another man's life? Indeed, thou hast done a terrible thing!"”

We now move to the sentence: حَتَّىٰ إِذَا لَقِيَا غُلَامًا (until when they met a boy -74). The word: غُلَام (ghulam) in the text is used for a minor boy in the Arabic usage. This boy killed by al-Khadir (علیہ السلام) was a minor - as corroborated by Sayyidna Ibn ` Abbas ؓ and most commentators. Further on, when the words: نَفْسًا زَكِيَّةً (innocent person) were used for him, that too supports the view that he was a minor. The reason is that زَكِيَّةً (zakiyyah) means 'free of sin' and it can be either the attribute of a prophet or a minor child who faces no accounting for what is done by him and no sin is written in his Book of Deeds.