The traditions that indicate when he reappears, he will look young and the passing of time will not make him old
Comprised of ten traditions
645. Kamāl al-dīn1: Muḥammad b. Muḥammad b. `Iṣām, from Muḥammad b. Ya`qūb al-Kulainī, from al-Qāsim b. al-`Alā, from Ismā’īl b. `Alī al-Qazwīnī, from `Alī b. Ismā’īl, from `Āṣim al-Ḥannāṭ, from Muḥammad b. Muslim al-Thaqafī al-Ṭaḥḥān, who recounts:
I went to see Abū Ja`far Muḥammad b. `Alī al-Bāqir, peace be upon him, with the intention of asking him about the Qā’im from the family of Muḥammad, Allah's blessings be on him and his family. He started the conversation [before I could ask my question]: “O Muḥammad b. Muslim! Surely in the Qā’im from the progeny of Muḥammad, there are customs [i.e. similarities] from five Messengers: Yūnus b. Mattā, Yūsuf b. Ya`qūb, Moses, Jesus, and Muḥammad, Allah’s blessings be on him and his family. As for the custom from Yūnus b. Mattā, it is his return after his occultation while he will [look] young despite his old age. As for the custom from Yūsuf b. Ya`qūb, it is his concealment from his close companions as well as the masses, his concealment from his brothers, and the difficult situation for his father Ya`qūb2 despite the little distance between him and his father, family, and followers.
As for the custom from Moses, it is the continuation of his fear, the lengthening of his occultation, the concealment of his birth, and the hardships his followers will experience after him from the tortures and degradations—until Allah, Mighty and Majestic be He, allows him to appear and gives him victory and assists him against his enemies. As for the custom from Jesus, peace be on him, it will be the differences people have concerning him, to the extent that a group will say, ‘He has not been born.’ Another group will say, ‘He has died,’ yet another will say, ‘He has been killed and crucified.’
As for the custom from his great grandfather, al-Mustafa Muḥammad, Allah’s blessings be on him and his family, it is his emergence with the sword and the slaying the enemies of Allah, the enemies of His Messenger, the oppressors and the tyrants, and that he will be helped with the sword and awe. His flag will never return defeated. From the signs of his emergence are: the emergence of al-Sufyānī from Syria, the emergence of al-Yamānī [from Yemen], a loud cry from the sky in the month of Ramaḍān, and an announcer calling out his name and the name of his father from the sky.”
646. Kamāl al-dīn3: Muḥammad b. Ibrāhīm b. Isḥāq al-Ṭāliqānī, from Aḥmad b. `Alī al-Anṣārī, from Abū l-Ṣalt al-Harawī who said:
I asked (Imam) al-Riḍā, peace be on him, “What are the signs of your Qā’im when he emerges?” He replied, “His sign is that he will be old in age [but] young in appearance. When someone looks at him he will guess his age to be forty years or less. And from his signs is that he will not become old with the passing of the days and nights until the arrival of his death.
647. `Iqd al-durar4: From Imam Abū `Abd-Allah al-Ḥusayn b. `Alī, peace be on him: “[When] the Mahdī rises, the people will refute him because he will return to them as a healthy youth. One of the greatest tests is that their master will emerge for them as a youth while they had thought he would be a very old man.”
648. Ghaybat al-Nu`mānī5: From Abū `Abd-Allah [al-Ṣādiq], peace be on him, in a tradition: “One of the greatest tests is that their master will emerge for them as a youth while they had considered him a very old person.”
649. Ghaybat al-Nu`mānī6: Narrated to us `Alī b. al-Ḥusayn al-Mas`ūdī, from Muḥammad b. Yaḥyā al-`Aṭṭār, from Muḥammad b. Ḥassān al-Rāzī, from Muḥammad b. `Alī al-Kūfī, from al-Ḥasan b. Maḥbūb, from `Abd-Allah b. Jabala, from `Alī b. Abī Ḥamza, from (Imam) Abū `Abd-Allah, peace be on him, who said: “[When] the Mahdī rises the people will refute him because he will return to them as a healthy youth. No one will keep faith in him except those whose covenant Allah has taken in the first [world of] particles (al-dharr al-awwal).”
650. Ghaybat al-Shaykh7: It has been narrated in a tradition that the Master of Time has a similarity with Jonah (Yūnus): “His return from his occultation while he is in the prime of his youth.”
Some of the traditions which we mentioned or will soon mention, interpret and clarify other traditions like the following two:
651. Ghaybat al-Shaykh8: Sa`d b. `Abd-Allah, from Muḥammad b. `Īsā b. `Ubaid, from Ismā’īl b. Abān, from `Amr b. Shimr, from Jābir al-Ju`fī, from (Imam) Abū Ja`far, peace be on him, who said:
Umar b. al-Khaṭṭāb asked Amīr al-Mu’minīn `Alī b. Abī Ṭālib, peace be on him, “Inform me about the Mahdī, what is his name?” He replied, “As for his name, my beloved took a covenant from me that I will not reveal his name until Allah sends him.” He then asked, “Then inform me about his attributes.” He replied, “He will be a young man of medium figure with beautiful hair that will flow over his shoulders. The light of his face will make the blackness of his beard and hair shine. May my father be sacrificed for the son of the best maid.”
652. Is`āf al-rāghibīn9: It has also been narrated about his characteristics that he is young, has applied kohl on his eyes, has arched eyebrows, an aquiline nose, a thick beard, and he will have a mole on his right cheek and another on his right hand.
The following traditions also prove the above concept: 539 and 555.