2) The Prophet (S) said: “al-Mahdi is one of us, the members of the household (Ahlul-Bayt).”

References: Sunan Ibn Majah, v2, Tradition #4085

It is evident from the above traditions that Imam al-Mahdi (as) is from the Ahlul-Bayt of Prophet Muhammad, so he can not be Jesus (the Messiah; al-Maseeh). Thus, al-Mahdi and Messiah are two different personalities but they come at the same time, al-Mahdi as Imam and Jesus as his follower. The following tradition clearly mentions that Imam al-Mahdi is one of descendants of the daughter of Prophet Muhammad (S):

3) The Prophet (S) said: The Mahdi will be of my family, of the descendants of Fatimah (the Prophet’s daughter).

References:

•  Sunan Abu Dawud, English version, Ch. 36, Tradition #4271 (narrated by Umm Salama, the wife of the Prophet)
•  Sunan Ibn Majah, v2, Tradition #4086
•  al-Nisa’i and al-Bayhaqi, and others as quoted in:
•  al-Sawa’iq al-Muhriqah, by Ibn Hajar al-Haythami, Ch. 11, section 1, p249

4) The Prophet (S) said: “The Mahdi will appear in my Ummah. He will appear for a minimum of 7 or a maximum of 9 years; at that time, my Ummah will experience a bountiful favor like never before. It shall have a great abundance of food, of which it need not save anything, and the wealth at that time is in great quantities, such that if a man asks the Mahdi to give him some, and the Mahdi (as) will say: Here! Take!”

References: Sunan Ibn Majah, v2, Tradition #5083

5) The Messenger of Allah said: “The world will not perish until a man among the Arabs appears whose name matches my name.”

References: Sahih al-Tirmidhi, v9, p74

6) The Prophet (S) said: “Allah will bring out from concealment al-Mahdi from my Family and just before the Day of Judgment; even if only one day were to remain in the life of the world, and he will spread on this earth justice and equity and will eradicate tyranny and oppression.”

References:

• Musnad Ahmad Ibn Hanbal, v1, p99

7) al-Hafidh Ibn Hajar al-Asqalani mentioned that:
“The Mahdi is of this Ummah, and that Jesus (S) will come down and pray behind him.”

References: Fat’h al-Bari, by Ibn Hajar al-Asqalani, v5, p362

8) Al-Saban in his book, “Is’af al-Raghibeen,”mentioned that: “The news about the appearance of the Mahdi are traceable back to the Prophet (S), and that he is one of the members of the family of the Prophet (S); and that he will fill the Earth with justice.”

9) Al-Suwaydi in his book, “Saba’iq al-Dhahab,”reported that: “The scholars have a consensus that the Mahdi (as) will appear at the end of time and fill the Earth with justice; and the traditions supporting his appearance are indeed numerous.”

10) al-HafidhAbul-Hasan Muhammad Ibn al-Husayn al-Sijistani al-Aburi al-Shafi’i (d. 363/974) said: “The traditions were related by numerous authorities and were spread far and wide by many narrators, from al-Mustafa (S) concerning al-Mahdi who is from the household (of the Prophet) and who will fill the world with justice..”
This statement was accepted by the subsequent scholars as testified by Ibn Hajar al-Asqalani (See Tahdhib al-Tahdhib, v9, p144; Fat’h al-Bari, v7, p305), al-Qurtubi (al-Tathkirah, p617), al-Suyuti (al-Hawi, v2, pp 165-166), al-Muttaqi al-Hindi (al-Burhan fi Alamat Mahdi Akhir al-Zaman, pp 175-176), Ibn Hajar al-Haythami (al-Sawa’iq al-Muhriqah, Ch. 11, section 1, p249), al-Zurqani (Sharh al-Mawahib al-Ladunniyyah, v5, p348), al-Sakhawi (Fat’h al-Mugheeth, v3, p41), etc.

11) Ibn Khaldoon (d. 808/1406), a famous historian, in whose book, “al-Muqaddamah,”wrote:
“Let it be known that it is a narrated event by ALL Muslims in EVERY era that at the end of time a man from the family of the Prophet (S) will, without fail, make his appearance and will strengthen Islam and spread justice; Muslims will follow him and he will gain domination over the Muslim realm. He will be called al-Mahdi.”(An Introduction to History, by Ibn Khaldoon, English version, London, 1967 Edition, pp 257-258)
The above quote proves that even Ibn Khaldoon was in the opinion that the belief in Imam al-Mahdi was not a characteristic of a special sect of Islam, but was a common belief to ALL Muslims.

12) Al-SayidSabiq, the Mufti for the “Muslim Brotherhood,”in his book, “al- ‘Aqa’id al-Islamiyyah,”that: “The idea about the Mahdi is indeed valid, and is one of the Islamic tenets that one must believe in.”Mr. Sabiq also narrated a variety of traditions relating to the appearance of al-Mahdi (as) in the above book.

13) at least 35 prominent Sunni scholars have written 46 of books exclusively about Imam al-Mahdi (as), the leader of our time. Here are some of the name of some of these books:
(1) “Kitab al-Mahdi,”by Abu Dawud.
(2)”Alamat al-Mahdi,”byJalaluddin al-Suyuti.
(3)”al-Qawl al-Mukhtasar fi Alamat al-Mahdi al-Muntadhar,”by Ibn Hajar.
(4)”Al-Bayan fi Akhbar Sahib al-Zaman,”by Allamah Abu Abdillah Ibn Muhammad Yusuf al-Ganji al-Shafi’i.
(5)”Iqd al-Durar fi Akbar al-Imam al-Muntadhar,”by Shaikh Jamaluddin Yusuf al-Damishqi.
(6)”Mahdi AaleRasool,”by ‘Ali Ibn Sultan Muhammad al-Harawi al-Hanafi.
(7)”Manaqib al-Mahdi,”by al-Hafidh Abu Nu’aym al-Isbahani.
(8)”Al-Burhan fi Alamat al-Mahdi Akhir al-Zaman,”by al-Muttaqi al-Hindi.
(9)”Arba’in Hadith fi al-Mahdi,”by Abdul Ala al-Hamadani.
(10)”Akhbar al-Mahdi,”by al-Hafidh Abu Nu’aym.