The Book of Occultation — al-Ṭūsī · Hadith 140 (#Ḥadīth #4)

78- وقال أحمد بن محمد بن أبي نصر: قال ابن النجاشي: من الإمام بعد صاحبكم؟ فدخلت على أبي الحسن الرضا عليه السلام فأخبرته،فقال: الإمام بعدي ابني؟ ثم قال: هل يجرؤ أحد أن يقول ابني وليس له ولد؟!

H 78 - Ahmad bin Muhammad bin Abi Nasr said: Ibn Najjashi asked: Who is the Imam after your companion [Imam Ridha ]? I went to Imam Ridha and asked about it. Imam said: The Imam after me is my son. After that he said: Can anyone who does not have a son, dare to say: ‘My son’?

Gradings are classical jarḥ-wa-taʿdīl, name-matched to a rijāl index (not individually re-verified).