Hadith 1:152
Sahīh (Zubair `Aliza'i)
He also reported God’s messenger as saying, “Islam began as a small religion and will return to the state in which it began. Then blessed will be the few [who hold to it]' Muslim transmitted it.
وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «بَدَأَ الْإِسْلَامُ غَرِيبًا وَسَيَعُودُ كَمَا بَدَأَ فَطُوبَى للغرباء» . رَوَاهُ مُسلم
Original Reference: Mishkat al-Masabih 159