Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
darimi:3234Sulaymān b. Ḥarb > Shuʿbah > Saʾalt al-Ḥakam And Ḥammād > al-Awliyāʾ Yujīzūn al-Waṣiyyah Faʾidhā Māt Lam Yujīzūā

[Machine] Regarding the guardians, they allow the will, but when he dies, they do not allow it? They said, "It is not permissible."  

الدارمي:٣٢٣٤حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ حَدَّثَنَا شُعْبَةُ قَالَ سَأَلْتُ الْحَكَمَ وَحَمَّادًا

عَنْ الْأَوْلِيَاءِ يُجِيزُونَ الْوَصِيَّةَ فَإِذَا مَاتَ لَمْ يُجِيزُوا؟ قَالَا «لَا يَجُوزُ»