Al-Kāfi - Volume 1 > Tacit and Explicit Testimony as proof of al-Hassan ibn Ali’s (a.s.) (a.s.) Divine Authority over the people after Amir al-Mu’minin Ali (a.s.)
Hadith #4

4ـ وَفِي نُسْخَةِ الصَّفْوَانِيِّ أَحْمَدُ بْنُ مُحَمَّدٍ عَنْ عَلِيِّ بْنِ الْحَكَمِ عَنْ سَيْفٍ عَنْ أَبِي بَكْرٍ عَنْ أَبِي عَبْدِ الله (عَلَيْهِ السَّلام) أَنَّ عَلِيّاً صَلَوَاتُ الله عَلَيْهِ حِينَ سَارَ إِلَى الْكُوفَةِ اسْتَوْدَعَ أُمَّ سَلَمَةَ كُتُبَهُ وَالْوَصِيَّةَ فَلَمَّا رَجَعَ الْحَسَنُ دَفَعَتْهَا إِلَيْهِ.

4. Ahmad ibn Muhammad has narrated from Ali ibn al-Hakam from Sayf from abu Bakr from abu ‘Abdallah (a.s.) who has said the following. “When Amir al-Mu’minin Ali (a.s.) was about to leave for Kufa he left in ’Umm Salama’s trust his books and his will. When al-Hassan (a.s.) returned to Madina she delivered all of them to him.”