Those who saw him while his father was still alive, peace be on them both
Comprised of twenty traditions
811. Kamāl al-dīn1: Narrated to us Muḥammad b. `Alī Mājīlawayh, may Allah be satisfied with him, from Muḥammad b. Yaḥyā al-`Aṭṭār, from Ja`far b. Muḥammad b. Mālik al-Fazārī, from Mu`āwiyat b. Ḥakīm, Muḥammad b. Ayyūb b. Nūḥ, and Muḥammad b. `Uthmān al-`Amrī, may Allah be satisfied with him, whom all said:
We were forty people in Abū Muḥammad al-Ḥasan b. `Alī’s house, peace be on him, when he showed us [his son] and said, “This is your Imam after me and my caliph upon you. Obey him and do not scatter after me regarding your religion otherwise you will perish. Know that you will not see him after this day.” After we left, barely a few days had gone by when Abū Muḥammad, peace be on him, passed away.
812. Al-Ṭūsī’s Ghayba2: From (Hibat-Allah b. Muḥammad, from a person that Aḥmad b. `Alī b. Nūḥ Abū l-`Abbās al-Sairāfī has narrated) and Ja`far b. Muḥammad b. Mālik al-Fazārī al-Bazzāz, from a group of Shias which include: `Alī b. Bilāl, Aḥmad b. Hilāl, Muḥammad b. Mu`āwiyat b. Ḥakīm, and al-Ḥasan b. Ayyūb b. Nūḥ (who narrated a long tradition) and all said:
We were forty people who had gathered around Abū Muḥammad al-Ḥasan b. `Alī, peace be on him, and were asking him about the Proof after him. `Uthmān b. Sa`īd al-Amrī stood up and pleaded, “O Son of Allah’s Messenger! I intend to ask you about an affair which you have more knowledge about than me.” He replied, “Sit down, O `Uthmān!” Then, enraged, he stood up to go out and ordered, “No one shall leave.” None of us left until some time had passed.
He then called `Uthmān—who stood up on his feet—and said, “Shall I inform you about the reason you came here?” They replied, “Yes, O Son of Allah’s Messenger.” He said, “You have come to ask me about the Divine Proof after me.” They replied in the affirmative. Suddenly a boy [appeared] who was like a part of the moon and of all the people, he resembled Imam Abū Muḥammad the most.
He said, “This is your Imam after me and my caliph upon you. Obey him and don’t scatter after me lest you perish in your religion. Beware! You will not see him after this day until he completes his age. Accept from `Uthmān what he will say, obey his orders, and accept his saying, because he is the successor of your Imam and the affair is in his hands . . .”
813. Kamāl al-dīn3: `Alī b. al-Ḥasan b. al-Faraj al-Mu’adhdhin, may Allah be satisfied with him, narrated to us from Muḥammad b. al-Ḥasan al-Karkhī, from Abū Hārūn—who is a man from our companions—who said: “I saw the Master of the Time and his face was shining like the full moon . . . (to the end of the tradition)”
814. Kamāl al-dīn4: Abū Ṭālib al-Muẓaffar b. Ja`far b. al-Muẓaffar al-`Alawī al-Samarqandī, may Allah be satisfied with him, from Ja`far b. Muḥammad b. Mas`ūd, from his father Muḥammad b. Mas`ūd al-`Ayyāshī, from Ādam b. Muḥammad al-Balkhī, from `Alī b. al-Ḥasan [al-Ḥusayn] b. Hārūn al-Daqqāq, from Ja`far b. Muḥammad b. `Abd-Allah b. al-Qāsim b. Ibrāhīm b. al-Ashtar, from Ya`qūb b. Manqūsh [Manfūs], who said:
I went to see Abū Muḥammad al-Ḥasan b. `Alī, peace be on him, while he was sitting on a bench in the house. On his right was a room with a drawn curtain. I asked him, “O my master! Who is the master of this affair?” He replied, “Raise the curtain.” When I raised the curtain, a boy emerged who was about five hand-spans tall and about ten or eight years old.
He had a wide forehead, white face, glittering eyes, and small hands and he had bent his knees. There was a mole on his right cheek and he had a forelock. He went and sat on Abū Muḥammad’s thigh, peace be on him, who said to me, “This is your Master.” He then leapt up and [the Imam] said to him, “Go inside until the appointed time.” He entered the room while I was [still] looking at him. [The Imam, peace be on him] said, “O Ya`qūb! See who is inside the room.” I went inside the room but found no one there!
815. Al-Kāfī5: `Alī b. Muḥammad, from Ja`far b. Muḥammad al-Kūfī, from Ja`far b. Muḥammad al-Makfūf, from `Amr al-Ahwāzī who said: “Abū Muḥammad, peace be on him, showed me his son and said, ‘This is your master after me.’”
816. Al-Kāfī6: `Alī b. Muḥammad, from al-Ḥusayn and Muḥammad—the sons of `Alī b. Ibrāhīm—from Muḥammad b. `Alī b. `Abd-al-Raḥmān al-`Abdī, a slave of Qays, from Ḍau’ b. `Alī al-`Ijlī, from a Persian man who he named, who said:
I went to Sāmarrā’ and stayed beside the door of Imam Abū Muḥammad’s house and he called me inside. I entered and greeted him and he asked, “What has brought you [here]?” I replied, “The desire to serve you.” He ordered me to be the doorkeeper. So I stayed in the house along with the servants and also [had the duty of] buying their needs from the market and when there were men in the house I would enter without permission.
One day, I went to him while he was in the men’s quarters and I heard some movement in the room. He suddenly called out to me, “Stay in your place and don’t move.” I didn’t dare to enter or go out. A slave-maid came out and with her was a covered thing. He then called out to me and said, “Come in,” and I went in. He called out to the slave-maid and she returned to him. He then said to her, “Uncover what you have with you.”
She removed the veil [which was covering] a white handsome boy. He uncovered his stomach and there was hair from his chest to his navel but it was green, not black. He said, “This is your master.” He then ordered her [to take him away] and she took him away. After this, I did not see him until Abū Muḥammad passed away.
817. Al-Kāfī7: `Alī b. Muḥammad, from Muḥammad b. Ismā’īl b. Mūsā b. Ja`far—who was a very old man from the descendants of the Messenger of Allah, Allah's blessings be on him and his family, in Iraq—who said: “I saw him between the two mosques, while he, peace be on him, was a young boy.”
818. Al-Kāfī8: Muḥammad b. Yaḥyā, from al-Ḥusayn b. Rizq-Allah Abū `Abd-Allah, from Mūsā b. Muḥammad b. al-Qāsim b. Ḥamzat b. Mūsā b. Ja`far, from Ḥakīma—(Imam) Muḥammad b. `Alī’s daughter and the aunt of [the Mahdī’s] father—who said she had seen him in the night of his birth and also after that.
819. Al-Kāfī9: Muḥammad b. Yaḥyā, from al-Ḥasan b. `Alī al-Nīsābūrī, from Ibrāhīm b. Muḥammad b. `Abd-Allah b. Mūsā b. Ja`far, from Abū Naṣr Ẓarīf—the servant—[who said] he had seen him, peace be on him.
820. Al-Kāfī10: `Alī b. Muḥammad from Fatḥ—the slave of al-Rāzī [al-Zurārī]—who said: “I heard Abū `Alī b. Muṭahhar mention that he had seen him and had described his height.”
The traditions with the following numbers also prove the above concept: 786–788, 796–797, 802, 804, and 808–810.