It is narrated from Qasim: A man asked his heirs if he could make a bequest of more than one-third; the heirs permitted him. Then, after his death, they withdrew their permission. Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) was asked about this, and he said: This is not permissible by compulsion. (That is, it is not permissible to compel in a bequest of more than one-third.)
Hadith Referenceسنن دارمي / من كتاب الوصايا / 3225
Hadith Gradingتحقیق (حسین سلیم أسد الدارانی):إسناده ضعيف لضعف عبد الرحمن بن عبد الله بن عتبة المسعودي، [مكتبه الشامله نمبر: 3236]
Hadith Takhrijعبدالرحمٰن بن عبداللہ بن عتبہ المسعودی کی وجہ سے اس اثر کی سند ضعیف ہے۔ ابونعیم کا نام فضل بن دکین ہے۔ دیکھئے: [ابن أبى شيبه 10781] ، [مجمع الزوائد 7183]