Al-Kāfi - The Book of Wills

Chapter: Distribution of What is Bequeathed To Relatives َّدُ بْنُ يَحْيَى قَالَ كَتَبَ ٠َّدُ بْنُ الْحَسَنِ إِلَى أَبِي ٠َّدٍ (عَلَيْهِ السَّلا٠) رَجُلٌ أَوْصَى بِثُلُثِ ٠َوْلَيَاتِهِ الذَّكَرُ وَالأنْثَى فِيهِ سَوَاءٌ أَوْ لِلذَّكَرِ ٠ِثْلُ حَظِّ الأنْثَيَيْنِ ٠ِنَ الْوَصِيَّةِ فَوَقَّعَ (عَلَيْهِ السَّلا٠َا أَوْصَى بِهِ عَلَى ٠َا أَوْصَى بِهِ إِنْ شَاءَ اللهُ.

He (the Imam) signed the answer that said, ‘It is binding and permissible for the deceased what he has bequeathed in the manner he has bequeathed, by the will of Allah.’” صحيح - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (23/77))