(2) The Book on Salat (Prayer)
كتاب الصلاة
(139) Chapter: What Has Been Related About 'What Is Between The East And The West Is A Qiblah'
(139) باب مَا جَاءَ أَنَّ مَا بَيْنَ الْمَشْرِقِ وَالْمَغْرِبِ قِبْلَةٌ
Jami` at-Tirmidhi 342 
Abu Hurairah narrated that :
Allah's Messenger said: "What is between the east and the west is Qiblah."
حَدَّثَنَا مُحَمَّدُ بْنُ أَبِي مَعْشَرٍ، حَدَّثَنَا أَبِي، عَنْ مُحَمَّدِ بْنِ عَمْرٍو، عَنْ أَبِي سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ مَا بَيْنَ الْمَشْرِقِ وَالْمَغْرِبِ قِبْلَةٌ ‏"‏ ‏.‏
Grade :  Sahih (Darussalam)
Reference : Jami` at-Tirmidhi 342
In-book reference : Book 2, Hadith 194
English translation : Vol. 1, Book 2, Hadith 342