Mahdi is from the Progeny of Fatemah – Holy Prophet (sawa)

The following tradition clearly mentions that Imam Mahdi is one of descendants of the daughter of Prophet Mohammed (sawa). He (sawa) said: The Mahdi will be of my family, of the descendants of Fatemah (the Prophet’s daughter).

References:

Sunan Abu Dawud, English version chapter 36 tradition no. 4271 (narrated by Umm Salma, the wife of the Prophet)
Sunan Ibn Majah volume 2 tradition no. 4086
al-Nisa’i and al-Bayhaqi, and others as quoted in al-Sawa’iq al-Muhriqah by Ibn Hajar al-Haythami chapter 11 section 1 page 249

Also:

The Prophet (sawa) said, We the children of Abd al-Muttalib are the Masters of the inhabitants of the heaven: Myself (sawa), Hamza, Ali (as), Jafar Ibn Abi Talib, Hasan (as), Husayn (as), and Mahdi (as).

References:

Sunan Ibn Majah volume 2 tradition no. 4087
al-Mustadrak by al-Hakim on the authority of Anas Ibn Malik
al-Daylami
al-Sawa’iq al-Muhriqah, by Ibn Hajar al-Haythami chapter 11 section 1 p245

Holy Prophet (sawa) said, “The Mahdi is from the progeny of Fatemah” (Sunan Ibne Majah chapter 34, Bab-ul Khurujul Mahdi, tradition 4086)

Holy Prophet (sawa) said, “We are the sons of Abdul Mauttalib, we are Ahlul Jannat (people of paradise). I, Hamza, Ali, Jafar, Hasan, Husain and Mahdi.” (Sunan Ibne Majah, chapter 34, Bab-ul Khurujul Mahdi, tradition 4087)

Holy Prophet (sawa) said, “Mahdi is from my progeny from the sons of Fatemah.” (Sunan Ibne Dawood, chapter Kitabul Mahdi, tradition 4284)

Holy Prophet (sawa) said, “Al Mahdi is from my progeny from the sons of Fatemah.” (Jameul Usool Fi Ahadees Rasul, chapter 7812)

Holy Prophet (sawa) said, “Al Mahdi is from my progeny from the sons of Fatemah.” (Eqdud Durrar Fi Akhbar al Muntazar tradition 1)

Holy Prophet (sawa) said, “Ya Fatemah! I am the last of prophet and the best of creation in front of Allah. The best of wasi and most beloved one of Allah is your husband. Our martyr is the best of all martyrs and beloved of Allah and he is Hamza ibne Abdul Muttalib, the uncle of your father and uncle of your husband. And from us is the one who is bestowed with two wings with which he flies wherever he wills with the angels in the Jannat and he is the son of the uncle of your father and brother of your husband and from is the chiefs of this Ummat and they are your sons, Hasan and Husain and they are the chief of the youth of Paradise and their father is better than both of them. Ya Fatemah, by the one who raised me surely from them is the Mahdi for this Ummat.” (Zakhaerul Uqba Fi Manaqib Zawil Qurba)

Holy Prophet (sawa) said, “O Fatemah! Mahdi is from your sons.” (Zakhaerul Uqba Fi Manaqib Zawil Qurba)

Holy Prophet (sawa) said, “The Mahdi is from my progeny and from the sons of Fatemah.” (Al Minarul Munif Fi Sahih Waz zae’ef by Al Imam Shamsuddin Abi Abdullah Mohd Ibne Abi Bakr Hanbali Damishqi, tradition 334)

Holy Prophet (sawa) said, “Al Mahdi is from my progeny and from the sons of Fatemah.” (Al Haawi lil Faqawi by Jalaluddin Abdur Rahman bin Abi Bakr bin Mohd Suyuti volume 2)

Holy Prophet (sawa) said, “Mahdi is from my sons. His face will be like a bright star.” (Mirqatul Mafaateh Sharhe Mishkaatul Masaabeh by Ali ibne Sultan Mohd Narwil Qari Hanafi Nooruddin volume 5 page 179)

Holy Prophet (sawa) said, The Mahdi is from my progeny and from the sons of Fatemah.” (Yanabiul Mawaddah by Hafiz Sulayman ibn Ibrahim Qunduzi Hanafi, chapter Babus Saalis Wa Saabun page 89)

Holy Prophet (sawa) said, Mahdi is from the sons of Fatemah.” (Yanabiul Mawaddah by Hafiz Sulayman ibn Ibrahim Qunduzi Hanafi, page 91, chapter Babus Saalis Wa Saabun)

Read more about Imam Mahdi in the Ahle Sunnah