A holistic approach to who the Mahdi is per Shiite hadiths and Quran.

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يَوْمَ نَدْعُو كُلَّ أُنَاسٍ بِإِمَامِهِمْ ۖ فَمَنْ أُوتِيَ كِتَابَهُ بِيَمِينِهِ فَأُولَٰئِكَ يَقْرَءُونَ كِتَابَهُمْ وَلَا يُظْلَمُونَ فَتِيلًا | The day We shall summon every group of people along with their imam, then whoever is given his book in his right hand—they will read it, and they will not be wronged so much as a single date-thread. | Al-Israa : 71

Some hadiths on this verse:

في الكافي عن الصادق عليه السلام قال بإمامهم الذي بين أظهرهم وهو قائم أهل زمانه.

In Al-Kafi from As-Sadiq (a) by the leader is among their presence and is the (qaeed) head of the people of his time.

والقمّي عن الباقر عليه السلام في هذه الآية قال يجيء رسول الله صلىَّ اللهُ عليه وآله وسلم في قومه وعليّ عليه السلام في قومه والحَسَن عليه السلام في قومه والحُسين عليه السلام في قومه وكلّ من ماتَ بين ظهرانيّ قوم جاؤا معه

And in Al-Qummi from Al-Baqir (a) regarding this verse, he said, The Messenger of God (s) will be brought to life with his people and Ali (a) with his people and Hassan (a) with with his people and Hussain (a) with his people and and whoever dies among his presense- they will come with him.

والعياشي ما يقرب من معناه.

And in Al-Ayashi what is close to that in meaning.

وفي الكافي والعياشي عن الباقر عليه السلام لما نزلت هذه الآية قال المسلمون يا رسول الله ألست إمام الناس كلّهم أجمعين فقال أنا رسول الله إلى الناس أجمعين ولكن سيكون من بعدي أئمّة على الناس من الله من أهل بيتي يقومون في الناس فيكذّبون ويظلمهم أئمّة الكفر والضلال وأشياعهم فمن والاهم واتبعهم وصدّقهم فهو مني ومعي وسيلقاني الا ومن ظلمهم وكذّبهم فليس منّي ولا معي وأنا منه بريء.

In Al-Kafi and Al-Ayashi from Al-Baqir (a) he said when this verse was revealed, the Muslims said O Messenger, are you not the leader of all people all together? So he said: I am a Messenger of God to all people all together but there will be after leaders upon the people from God from the people of my house, they will rise among the people so they will be denied and oppressed by the leaders of disbeliever and error and their followers so whoever gives authority to them and follows them and believes so he is from me and with me and will meet me, however, whoever oppresses them and denies them so he is not from me and nor with me and I am quit/free from him.

 

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Salam

Some hadiths about Jesus (a):

Shahr ibn Hawshab said, “Al-Hajjaj said to me, ‘There is a verse in the Book of Allah that has wearied me.’ I said, ‘O Commander! Which verse is it?’ He said, ‘His saying,

‘And there is not one of the followers of the Book but most certainly believes in this before his death, and on the day of resurrection he (Jesus) shall be a witness against them. (4:159)’

By Allah! I command a Jew and a Christian to be beheaded, then I look at them with my own eyes, but I do not see them moving their lips when they die.’ I said, ‘May Allah reform the Commander! It is not as you have interpreted it.’ He said, ‘How is it?’

I said, ‘Verily, Jesus will descend to the world before the Resurrection Day, then the people of the Jewish nation or Christian nation will not remain [on the earth] unless they believe in him before his death and will pray behind al-Mahdi.’ He said, ‘Woe unto you! Where did you bring it from?’ I said, ‘Muhammad ibn ‘Ali ibn al-Husayn ibn ‘Ali ibn Abu Talib (‘a) narrated it to me.’ He said, ‘By Allah! You brought it from a pure spring.’”1

2. The Apostle of Allah (S) said, “Good news for you. [He repeated it three times.] … How can the community of which I am the first perish? There are twelve persons after me who are felicitous and possess understanding and Christ Jesus the son of Mary is at the end of them. But between them, the children of confusion will perish. They are not from me and I am not from them.”2

3. The Apostle of Allah said, “How can a community perish when I am at the beginning of it, Jesus the son of Mary will be at the end of it and al-Mahdi will be in the middle of it.”3

4. Hudhayfah ibn ’Usayd al-Ghifari said, “We sat in the shadow of a wall in al-Madinah and the Apostle of Allah (S) was in a room. Then he appeared over us and said, ‘What are you doing?’ We said, ‘We are talking.’ He said, ‘About what?’ We said, ‘About the Resurrection Day (al-Sa‘ah).’

He said, ‘You will not see the Resurrection Day until you see ten signs before it, sunrise from the West, al-Dajjal and the beast of the earth, three lunar eclipses on the earth, one in the East, one in the West and one in the Arabian Peninsula and the emergence of Jesus the son of Mary (‘a) …”4

5. Abu al-Qasim al-Ta’i said, “I asked ‘Ali ibn Musa Al-Ridha’ about he who will fight with us. He said, “He who will fight with the companion of Jesus the son of Mary.”5

6. It is reported that Abu ‘Abd Allah (‘a) said, “Jesus the son of Mary is the Spirit of Allah and His Word. He was thirty-three years old in the world. Then Allah raised him to heaven. He will descend to the earth and it is he who will kill the Antichrist (Dajjal.)”6

7. Abu Ja‘far (‘a) about the verse

O you who believe! Be helpers of Allah, as Jesus the son of Mary said to his disciples, ‘Who will be my helpers in the cause of Allah?’ The disciples said, We are the helpers of Allah. So, a party of the children of Israel believed and another party disbelieved. Then We aided those who believed against their enemy, and they became uppermost (61:14)

said, “The group that became disbelievers was the group that killed and crucified one who was similar to Jesus (‘a). The group that became believers was the group [one of whose members] accepted the one who was like Jesus so that he would not be killed. Then the group that killed and crucified him was killed. This is [the explanation of] His saying,

Then We aided those who believed against their enemy, and they became uppermost.(61:14)7

8. It is reported that Jesus will say to al-Mahdi, “I was raised as a minister not as a commander.”8

9. Hudhayfah reported that the Prophet (S) said, “Al-Mahdi will turn his face to Jesus when he descends as if water were dropping from his hair, and will say to him, ‘Go ahead and say the prayer.’ Jesus will say, ‘The prayer has been set up only for you.’ So, Jesus will pray behind a man who is among my sons.”9

10 It is reported that Ka‘b said, “Jesus will descend from heaven. Then the Jews and Christians will come to him and say, ‘We are your people.’ He will say, ‘You lie. The emigrants, the rest of the people of battles, are my people.’

Then Jesus will come to the place that the Muslims are gathered and find their Caliph10 is praying with them, who will say to him, ‘O Christ! Pray in front of us.’ He will say, ‘But you pray with your people. I have been raised as a minister, not as a commander.’11

11. The Apostle of Allah (S) said, “…The leader of the people on that day will be a righteous man. It will be said that he prays the morning prayer. When he says “Allah Akbar” and begins to pray, Jesus the son of Mary (‘a) will descend. When the righteous man sees him, he will know him, return and walk back. Then Jesus (‘a) will come, put his hand between his shoulders and say, ‘Pray. The prayer has been set up for you.’ Then Jesus will pray behind him and say, ‘Open the door.’ Then they will open the door.”12

12. It is reported that, “Jesus (‘a) will descend, wearing two saffron colored robes.” According to another tradition, “Jesus the son of Mary will descend to a hill of the Sacred Earth that is named Ithbani [or Ithbayt]. Two yellow dresses are on him and the hair of his head is anointed and there is a lance (arm) in his hand by which he kills Dajjal.

He comes to Jerusalem while the people pray the afternoon prayer and Imam is in front of them. Imam comes back, but Jesus prefers him and prays behind him according to the revealed law of Muhammad. Then he will kill the swine, break the crosses, destroy the churches and temples and kill the Christians unless they believe in him.”13

13. Tha‘labi mentioned in his Tafsir with its own chain of transmission regarding “Ha mim ‘ayn sin qaf,”14 “Al-sin is the gleam of Mahdi and al-qaf is the power of Jesus (‘a) when he descends, kills the Christians15 and ruins the churches.”16

14. It is reported that the Prophet (S) said, “Among my progeny is the Mahdi. When he emerges, Jesus the son of Mary will descend to help him, then Jesus will send him ahead and pray behind him.”17

15. It is reported from Abu ‘Abd Allah from his fathers that Hasan the son of ‘Ali (‘a) said when disputing with the king of Byzantium, “The life of Jesus in the world was thirty-three years. Then Allah raised him to heaven and he will descend to the earth in Damascus, and it is he who will kill the Antichrist (Dajjal).”18

16. Khaythama reported that Abu Ja‘far said, “…O Khaythama! There will come a time for the people when they will not know who is Allah and His unity until Dajjal appears and Jesus the son of Mary, may peace and blessings be with both of them, descends from the sky, and Allah will kill Dajjal by his hands and a man that is from our House will pray with the people. Do you not know that Jesus will pray behind us, although he is a prophet? Beware that we are better than him.”19