Sahih al-Bukhari, Volume 4, Book 55, Hadith 566 (USC-MSA) ⓘ
Narrated Abu Huraira: The Prophet said, "Allah has made an opening in the wall of the Gog and Magog (people) like this, and he made with his hand (with the help of his fingers).
حَدَّثَنَا مُسْلِمُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا وُهَيْبٌ، حَدَّثَنَا ابْنُ طَاوُسٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " فَتَحَ اللَّهُ مِنْ رَدْمِ يَأْجُوجَ وَمَأْجُوجَ مِثْلَ هَذَا " . وَعَقَدَ بِيَدِهِ تِسْعِينَ.
also referenced under: Book 60, Hadith 27 (In-Book) & Hadith 3347 (DarusSalam)