Al-Kāfi - Volume 1 > Tacit and Explicit Testimony as proof of abu ‘Abdallah Ja‘far ibn Muhammad al-Sadiq’s (a.s.) Divine Authority over the people after Muhammad ibn Ali ibn al-Husayn (a.s.)
Hadith #7

7ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ ابْنِ مَحْبُوبٍ عَنْ هِشَامِ بْنِ سَالِمٍ عَنْ جَابِرِ بْنِ يَزِيدَ الْجُعْفِيِّ عَنْ ابي جعفر (عَلَيْهِ السَّلام) قَالَ سُئِلَ عَنِ الْقَائِمِ (عَلَيْهِ السَّلام) فَضَرَبَ بِيَدِهِ عَلَى أَبِي عَبْدِ الله (عَلَيْهِ السَّلام) فَقَالَ هَذَا وَالله قَائِمُ آلِ مُحَمَّدٍ (صَلَّى اللهُ عَلَيْهِ وَآلِه) قَالَ عَنْبَسَةُ فَلَمَّا قُبِضَ أَبُو جَعْفَرٍ (عَلَيْهِ السَّلام) دَخَلْتُ عَلَى أَبِي عَبْدِ الله (عَلَيْهِ السَّلام) فَأَخْبَرْتُهُ بِذَلِكَ فَقَالَ صَدَقَ جَابِرٌ ثُمَّ قَالَ لَعَلَّكُمْ تَرَوْنَ أَنْ لَيْسَ كُلُّ إِمَامٍ هُوَ الْقَائِمَ بَعْدَ الامَامِ الَّذِي كَانَ قَبْلَهُ.

7. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from ibn Mahbub from Hisham ibn Salim from Jabur ibn Yazid al-Ju‘fiy who has said the following. “A question was asked (from abu Ja‘far (a.s.) about al-Qa’im (the twelfth Imam (a.s.). He (abu Ja‘far) tapped (at the shoulder of) abu ‘Abdallah (a.s.) and said, “This, by Allah, is the Qa’im (one who will establish the kingdom of Allah) of the family of Muhammad (s.a.).” ‘Anbasa has said, “when abu Ja‘far passed away, went to see abu ‘Abdallah (a.s.) and told him of what I had heard (from Jabur). The Imam (a.s.) said, “Jabur has spoken the truth.” He then said, “You perhaps think that the every succeeding Imam after a preceding Imam is not al-Qa’im (also meaning the one who obeys and serves Allah).”