Sahih al-Bukhari 2743
Sahih al-Bukhari · Book 55: Wills and Testaments (Wasaayaa) · To will one-third of one's property
Narrated Ibn `Abbas:
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ ، حَدَّثَنَا سُفْيَانُ ، عَنْ هِشَامِ بْنِ عُرْوَةَ ، عَنْ أَبِيهِ ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ قَالَ لَوْ غَضَّ النَّاسُ إِلَى الرُّبْعِ، لأَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " الثُّلُثُ، وَالثُّلُثُ كَثِيرٌ أَوْ كَبِيرٌ " .
I recommend that people reduce the proportion of what they bequeath by will to the fourth (of the whole legacy), for Allah's Messenger (ﷺ) said, "One-third, yet even one third is too much."