The Sufficient (Vol 1) · Hadith 461 (#Ḥadīth #5)
Chapter 6 | The Issue that even if only two people would remain on earth one of them would certainly be the Imam, the person with divine authority
5ـ أَحْمَدُ بْنُ مُحَمَّدٍ عَنْ مُحَمَّدِ بْنِ الْحَسَنِ عَنِ النَّهْدِيِّ عَنْ أَبِيهِ عَنْ يُونُسَ بْنِ يَعْقُوبَ عَنْ أَبِي عَبْدِ الله قَالَ سَمِعْتُهُ يَقُولُ لَوْ لَمْ يَكُنْ فِي الارْضِ إِلا اثْنَانِ لَكَانَ الامَامُ أَحَدَهُمَا.
Ahmad ibn Muhammad has narrated from Muhammad ibn al-Hassan from al-Nahdi from his father from Yunus ibn ya‘qub from abu ‘Abdallah who has said the following. “Would there remain no one except two people one of them will certainly be the Imam.”
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).