Sahih Muslim , Hadith 146 ⓘ
It is narrated on the authority of Ibn 'Umar ('Abdullah b. 'Umar) that the Messenger of Allah observed: Verily Islam started as something strange and it would again revert (to its old position) of being strange just as it started, and it would recede between the two mosques just as the serpent crawls back into its hole.
وَحَدَّثَنِي مُحَمَّدُ بْنُ رَافِعٍ، وَالْفَضْلُ بْنُ سَهْلٍ الأَعْرَجُ، قَالاَ حَدَّثَنَا شَبَابَةُ بْنُ سَوَّارٍ، حَدَّثَنَا عَاصِمٌ، - وَهُوَ ابْنُ مُحَمَّدٍ الْعُمَرِيُّ - عَنْ أَبِيهِ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِنَّ الإِسْلاَمَ بَدَأَ غَرِيبًا وَسَيَعُودُ غَرِيبًا كَمَا بَدَأَ وَهُوَ يَأْرِزُ بَيْنَ الْمَسْجِدَيْنِ كَمَا تَأْرِزُ الْحَيَّةُ فِي جُحْرِهَا " .
also referenced under: Book 1, Hadith 280 (In-Book) & Book 1, Hadith 271 (USC-MSA)