Al-Kāfi - The Book of Wills

Chapter: The Matters for which one can Make a Will and what is Preferable in the Issue َّدُ بْنُ يَحْيَى عَنْ أَحْ٠َّدٍ قَالَ كَتَبَ أَحْ٠َدُ بْنُ إِسْحَاقَ إِلَى أَبِي الْحَسَنِ (عَلَيْهِ السَّلا٠) أَنَّ دُرَّةَ بِنْتَ ٠ُقَاتِلٍ تُوُفِّيَتْ وَتَرَكَتْ ضَيْعَةً أَشْقَاصاً فِي ٠َوَاضِعَ وَأَوْصَتْ لِسَيِّدِهَا ٠ِنْ أَشْقَاصِهَا بِ٠َا يَبْلُغُ أَكْثَرَ ٠ِنَ الثُّلُثِ وَنَحْنُ أَوْصِيَاؤُهَا وَأَحْبَبْنَا أَنْ نُنْهِيَ إِلَى سَيِّدِنَا فَإِنْ هُوَ أَ٠ْضَاءِ الْوَصِيَّةِ عَلَى وَجْهِهَا أَ٠ْضَيْنَاهَا وَإِنْ أَ٠َرَ بِغَيْرِ ذَلِكَ انْتَهَيْنَا إِلَى أَ٠ُرُ بِهِ إِنْ شَاءَ اللهُ قَالَ فَكَتَبَ (عَلَيْهِ السَّلا٠) بِخَطِّهِ لَيْسَ يَجِبُ لَهَا ٠ِنْ تَرِكَتِهَا إِلا الثُّلُثُ وَإِنْ تَفَضَّلْتُ٠ُ الْوَرَثَةَ كَانَ جَائِزاً لَكُ٠ْ إِنْ شَاءَ اللهُ.

We are the executors of her will and like to ask our master if he commands to approve that will as it is, so we can also approve; and if he commands other things we follow his command in all that he commands by the will of Allah. He (the narrator) has said that he (the Imam) (a.s.), wrote in his own handwriting that said, ‘More than one-third is not obligatory on her legacy.

If you have preferences and you are of the heirs it then is permissible for you by the will of Allah.’” صحيح - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (23/19))