The Sufficient (Vol 1) · Hadith 750 (#Ḥadīth #3)
Chapter 63 | Proof that Imamat (leadership with Divine Authority) Continues in the Descendents of the Preceding Imam but not through his Brother or Paternal Uncle or other such Relatives
3ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ عِيسَى عَنْ مُحَمَّدِ بْنِ إِسْمَاعِيلَ بْنِ بَزِيعٍ عَنْ أَبِي الْحَسَنِ الرِّضَا أَنَّهُ سُئِلَ أَ تَكُونُ الامَامَةُ فِي عَمٍّ أَوْ خَالٍ فَقَالَ لا فَقُلْتُ فَفِي أَخٍ قَالَ لا قُلْتُ فَفِي مَنْ قَالَ فِي وَلَدِي وَهُوَ يَوْمَئِذٍ لا وَلَدَ لَهُ.
3. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad ibn ‘Isa from Muhammad ibn Isma‘il ibn Bazi‘ who has said the following. “Abu al-Hassan al-Rida was once asked, “Can Imamat continue in uncles?” He replied, “No, it can not happen.” The narrator has said that he asked the Imams , “Can it continue in a brother?” He replied, “No, it can not happen.” I then asked, “With who then it can continues?” He replied, “It will continue with my children.” In those days he hadd no children.”
Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).