وَ رَوَى مُحَمَّدُ بْنُ أَبِي عُمَيْرٍ عَنْ أَبِي الْمَغْرَاءِ عَنْ أَبِي بَصِيرٍ عَنْ أَبِي عَبْدِ اللَّهِ ع أَنَّهُ قَالَ إِذَا بَلَغَ الْغُلَامُ عَشْرَ سِنِينَ فَأَوْصَى بِثُلُثِ مَالِهِ فِي حَقٍّ جَازَتْ وَصِيَّتُهُ وَ إِذَا كَانَ ابْنَ سَبْعِ سِنِينَ فَأَوْصَى مِنْ مَالِهِ بِالْيَسِيرِ فِي حَقٍّ جَازَتْ وَصِيَّتُهُ.
English translationBab Ul Qaim Publications
Hadith.5452 - Muhammad ibn Abi Umayr narrated from Abi Al-Maghra from Abu Baṣir from Abu Abdullah Imam Jafar ibn Muhammad Al-Sadiq (as), who said: "If a boy reaches the age of ten and makes a will for one-third of his wealth in a rightful cause, his will is valid. And if he is seven years old and makes a will for a small amount of his wealth in a rightful cause, his will is also valid."
Translation: Bab Ul Qaim Publications·Thaqalayn link·The Arabic above is the original.