كتاب الإيمان
1
The Book of Faith
(71)
Chapter: The descent of 'Eisa bin Mariam to judge according to the Shari'ah of our Prophet Muhammad (saws); And how Allah has honored this Ummah; And clarifying the evidence that this religion will not be abrogated; and that a group from it will continue to adhere to the truth and prevail until the day of resurrection
(71)
باب نُزُولِ عِيسَى ابْنِ مَرْيَمَ حَاكِمًا بِشَرِيعَةِ نَبِيِّنَا مُحَمَّدٍ صلى الله عليه وسلم

It is narrated on the authority of Abu Huraira that the Messenger of Allah (ﷺ) observed:

What will be your state when the son of Mary descends amongst you and there will be an Imam amongst you?
حَدَّثَنِي حَرْمَلَةُ بْنُ يَحْيَى، أَخْبَرَنَا ابْنُ وَهْبٍ، أَخْبَرَنِي يُونُسُ، عَنِ ابْنِ شِهَابٍ، قَالَ أَخْبَرَنِي نَافِعٌ، مَوْلَى أَبِي قَتَادَةَ الأَنْصَارِيِّ أَنَّ أَبَا هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ كَيْفَ أَنْتُمْ إِذَا نَزَلَ ابْنُ مَرْيَمَ فِيكُمْ وَإِمَامُكُمْ مِنْكُمْ ‏"‏ ‏.‏
Reference : Sahih Muslim 155 d
In-book reference : Book 1, Hadith 299
USC-MSA web (English) reference : Book 1, Hadith 290
  (deprecated numbering scheme)