The Mahdī will lead the ummah as one
that the Messenger of Allah ﷺ said, "What would you do when ˹Jesus˺ the son of Mary would descend amongst you and would lead you as one amongst you?" Ibn Abū Dhiʾb on the authority of Abū Hurayrah narrated: "Your Imām (leader) amongst you."
Ibn Abū Dhiʾb said: Do you know what the words: "He would lead as one amongst you" mean? I said: Explain these to me. He said: He would lead you according to the Book of your Lord ﷻ and the Sunnah of your Prophet ﷺ.
أَنَّ رَسُولَ اللَّهِ ﷺ: قَالَ «كَيْفَ أَنْتُمْ إِذَا نَزَلَ فِيكُمُ ابْنُ مَرْيَمَ فَأَمَّكُمْ مِنْكُمْ۔» فَقُلْتُ لاِبْنِ أَبِي ذِئْبٍ إِنَّ الأَوْزَاعِيَّ حَدَّثَنَا عَنِ الزُّهْرِيِّ عَنْ نَافِعٍ عَنْ أَبِي هُرَيْرَةَ: «وَإِمَامُكُمْ مِنْكُمْ۔»
قَالَ ابْنُ أَبِي ذِئْبٍ تَدْرِي «مَا أَمَّكُمْ مِنْكُم؟»، قُلْتُ: تُخْبِرُنِي۔ قَالَ: فَأَمَّكُمْ بِكِتَابِ رَبِّكُمْ تَبَارَكَ وَتَعَالَى وَسُنَّةِ نَبِيِّكُمْ ﷺ۔