(25) The Book of Jihad
كتاب الجهاد
(42) Chapter: Fighting The Turks And The Ethiopians
(42) باب غَزْوَةِ التُّرْكِ وَالْحَبَشَةِ ‏.‏
Sunan an-Nasa'i 3177 
It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said:
"The Hour will not begin until the Muslims fight the Turks, a people with faces like hammered shields who wear clothes made of hair and shoes made of hair."
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا يَعْقُوبُ، عَنْ سُهَيْلٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ لاَ تَقُومُ السَّاعَةُ حَتَّى يُقَاتِلَ الْمُسْلِمُونَ التُّرْكَ قَوْمًا وُجُوهُهُمْ كَالْمَجَانِّ الْمُطَرَّقَةِ يَلْبَسُونَ الشَّعَرَ وَيَمْشُونَ فِي الشَّعَرِ ‏"‏ ‏.‏
Grade :  Sahih (Darussalam)
Reference : Sunan an-Nasa'i 3177
In-book reference : Book 25, Hadith 93
English translation : Vol. 1, Book 25, Hadith 3179