كتاب الإيمان
1  
The Book of Faith
(21)
Chapter: People excel over one another in faith, and the superiority of the people of Yemen in faith
(21)
باب تَفَاضُلِ أَهْلِ الإِيمَانِ فِيهِ وَرُجْحَانِ أَهْلِ الْيَمَنِ فِيهِ ‏
Sahih Muslim 52 d

It is narrated on the authority of Abu Huraira that the Messenger of Allah (may peace and blessings be upon him) remarked:

The summit of unbelief is towards the East and the pride and conceitedness is found among the owners of horses and camels who are rude and uncivil, people of the tents, and tranquillity is found among those who rear goats and sheep.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ رَأْسُ الْكُفْرِ نَحْوَ الْمَشْرِقِ وَالْفَخْرُ وَالْخُيَلاَءُ فِي أَهْلِ الْخَيْلِ وَالإِبِلِ الْفَدَّادِينَ أَهْلِ الْوَبَرِ وَالسَّكِينَةُ فِي أَهْلِ الْغَنَمِ ‏"‏ ‏.‏
Reference : Sahih Muslim 52d
In-book reference : Book 1, Hadith 92
USC-MSA web (English) reference : Book 1, Hadith 87
  (deprecated numbering scheme)