Jami` at-Tirmidhi 3150
جامع الترمذي#3150Sahihحَدَّثَنَا أَبُو حَفْصٍ، عَمْرُو بْنُ عَلِيٍّ حَدَّثَنَا أَبُو قُتَيْبَةَ، سَلْمُ بْنُ قُتَيْبَةَ حَدَّثَنَا عَبْدُ الْجَبَّارِ بْنُ الْعَبَّاسِ الْهَمْدَانِيُّ، عَنْ أَبِي إِسْحَاقَ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ، عَنْ أُبَىِّ بْنِ كَعْبٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " الْغُلاَمُ الَّذِي قَتَلَهُ الْخَضِرُ طُبِعَ يَوْمَ طُبِعَ كَافِرًا " . قَالَ أَبُو عِيسَى هَذَا حَدِيثٌ حَسَنٌ صَحِيحٌ غَرِيبٌ .
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
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 47:202