Sunan Ibn Majah 2510
سنن ابن ماجه#2510Sahihحَدَّثَنَا نَصْرُ بْنُ عَلِيىٍّ الْجَهْضَمِيُّ، حَدَّثَنَا أَبُو أَحْمَدَ، عَنْ إِسْرَائِيلَ، عَنْ سِمَاكٍ، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " فِي الرِّكَازِ الْخُمُسُ " .
It was narrated from Ibn`Abbas that the Messenger of Allah (ﷺ) said:“One fifth is due on buried treasure.”
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:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Zubair Ali ZaiSahih
In-book reference: 18:9