كَتَبَ مُحَمَّدُ بْنُ اَلْحَسَنِ اَلصَّفَّارُ رَضِيَ اَللَّهُ عَنْهُ إِلَى أَبِي مُحَمَّدٍ اَلْحَسَنِ بْنِ عَلِيٍّ عَلَيْهِ اَلسَّلاَمُ: رَجُلٌ أَوْصَى إِلَى رَجُلَيْنِ أَ يَجُوزُ لِأَحَدِهِمَا أَنْ يَنْفَرِدَ بِنِصْفِ اَلتَّرِكَةِ وَ اَلْآخَرِ بِالنِّصْفِ فَوَقَّعَ عَلَيْهِ اَلسَّلاَمُ "لاَ يَنْبَغِي لَهُمَا أَنْ يُخَالِفَا اَلْمَيِّتَ وَ يَعْمَلاَنِ عَلَى حَسَبِ مَا أَمَرَهُمَا إِنْ شَاءَ اَللَّهُ".
Muhammad ibn Al-Hasan Al-Ṣaffar (may Allah (swt) be pleased with him) wrote to Abu Muhammad Imam Hasan ibn Ali Al-Askari (a.s) asking: "A man appointed two individuals as executors of his will. Is it permissible for one of them to independently handle half of the inheritance and the other to manage the other half?" Imam (a.s) responded in writing: "It is not appropriate for them to act contrary to the deceased's instructions. They should act according to what he commanded them, God willing."