Sunan an-Nasa'i 3631
It was narrated that Sa'd bin Abi Waqqas said:
"The Messenger of Allah visited me when I was sick, and said: 'Have you made a will?' I said: 'Yes.' He said: 'How much?' I said: 'For all my wealth to be given in the cause of Allah.' He said: 'What have you left for your children?' I said: 'They are rich (independent of means).' He said: 'Bequeath one-tenth.' And we kept discussing it until he said: 'Bequeath one-third, and one-third is much or large.'"
أَخْبَرَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، قَالَ أَنْبَأَنَا جَرِيرٌ، عَنْ عَطَاءِ بْنِ السَّائِبِ، عَنْ أَبِي عَبْدِ الرَّحْمَنِ، عَنْ سَعْدِ بْنِ أَبِي وَقَّاصٍ، قَالَ عَادَنِي رَسُولُ اللَّهِ ﷺ فِي مَرَضِي فَقَالَ " أَوْصَيْتَ ". قُلْتُ نَعَمْ. قَالَ " بِكَمْ ". قُلْتُ بِمَالِي كُلِّهِ فِي سَبِيلِ اللَّهِ. قَالَ " فَمَا تَرَكْتَ لِوَلدِكَ ". قُلْتُ هُمْ أَغْنِيَاءُ. قَالَ " أَوْصِ بِالْعُشْرِ ". فَمَا زَالَ يَقُولُ وَأَقُولُ حَتَّى قَالَ " أَوْصِ بِالثُّلُثِ وَالثُّلُثُ كَثِيرٌ أَوْ كَبِيرٌ ".