Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
ibnmajah:4086Abū Bakr b. Abū Shaybah > Aḥmad b. ʿAbd al-Malik > Abū al-Malīḥ al-Raqqī > Ziyād b. Bayān > ʿAlī b. Nufayl > Saʿīd b. al-Musayyab

"We were with Umm Salamah and we were discussing Mahdi. She said: 'I heard the Messenger of Allah ﷺ say: "Mahdi will be one of the descendents of Fatimah."  

ابن ماجة:٤٠٨٦حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ حَدَّثَنَا أَحْمَدُ بْنُ عَبْدِ الْمَلِكِ حَدَّثَنَا أَبُو الْمَلِيحِ الرَّقِّيُّ عَنْ زِيَادِ بْنِ بَيَانٍ عَنْ عَلِيِّ بْنِ نُفَيْلٍ عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ قَالَ

كُنَّا عِنْدَ أُمِّ سَلَمَةَ فَتَذَاكَرْنَا الْمَهْدِيَّ فَقَالَتْ سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ الْمَهْدِيُّ مِنْ وَلَدِ فَاطِمَةَ