أَخْبَرَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنِ ابْنِ عَبَّاسٍ، قَالَ لَوْ غَضَّ النَّاسُ إِلَى الرُّبُعِ لأَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏
"‏ الثُّلُثَ وَالثُّلُثُ كَثِيرٌ أَوْ كَبِيرٌ ‏"‏‏.‏

It was narrated that Ibn 'Abbas said: "If the people were to reduce (their bequests) to one-quarter (of their wealth, that would be better), because the Messenger of Allah said: 'One-third, and one-third is much or large.'"