Al-Kāfi - The Book of Wills

Chapter: The Case of One’s Appointing Two Executors for the Will, Each of whom Deals with a Certain Portion of the Legacy َّدُ بْنُ يَحْيَى قَالَ كَتَبَ ٠َّدُ بْنُ الْحَسَنِ إِلَى أَبِي ٠َّدٍ (عَلَيْهِ السَّلا٠َاتَ وَأَوْصَى إِلَى رَجُلَيْنِ أَيَجُوزُ لأحَدِهِ٠َا أَنْ يَنْفَرِدَ بِنِصْفِ التَّرِكَةِ وَالآخَرِ بِالنِّصْفِ فَوَقَّعَ (عَلَيْهِ السَّلا٠) لا يَنْبَغِي لَهُ٠َا أَنْ يُخَالِفَا الْ٠َيِّتَ وَأَنْ يَعْ٠َلا عَلَى حَسَبِ ٠َا إِنْ شَاءَ اللهُ.

They must work as they are instructed, by the will of Allah.’” صحيح - Allamah Baqir al-Majlisi (Mirʾāt al-ʿUqūl fī Sharḥ Akhbār Āl al-Rasūl (3/78))