كتاب الإيمان
1  
The Book of Faith
(15)
Chapter: Clarification of those characteristics which, if a person attains them, he will find the sweetness of faith
(15)
باب بَيَانِ خِصَالٍ مَنِ اتَّصَفَ بِهِنَّ وَجَدَ حَلاَوَةَ الإِيمَانِ
Sahih Muslim 43 a

It is reported on the authority of Anas that the Prophet of Allah (may peace and blessings be upon him ) said:

There are three qualities for which anyone who is characterised by them will relish the sweetness of faith: he to whom Allah and His Messenger are dearer than all else; he who loves a man for Allah's sake alone; and he who has as great an abhorrence of returning to unbelief after Allah has rescued him from it as he has of being cast into Hell.
حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ، وَمُحَمَّدُ بْنُ يَحْيَى بْنِ أَبِي عُمَرَ، وَمُحَمَّدُ بْنُ بَشَّارٍ، جَمِيعًا عَنِ الثَّقَفِيِّ، - قَالَ ابْنُ أَبِي عُمَرَ حَدَّثَنَا عَبْدُ الْوَهَّابِ، - عَنْ أَيُّوبَ، عَنْ أَبِي قِلاَبَةَ، عَنْ أَنَسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ ثَلاَثٌ مَنْ كُنَّ فِيهِ وَجَدَ بِهِنَّ حَلاَوَةَ الإِيمَانِ مَنْ كَانَ اللَّهُ وَرَسُولُهُ أَحَبَّ إِلَيْهِ مِمَّا سِوَاهُمَا وَأَنْ يُحِبَّ الْمَرْءَ لاَ يُحِبُّهُ إِلاَّ لِلَّهِ وَأَنْ يَكْرَهَ أَنْ يَعُودَ فِي الْكُفْرِ بَعْدَ أَنْ أَنْقَذَهُ اللَّهُ مِنْهُ كَمَا يَكْرَهُ أَنْ يُقْذَفَ فِي النَّارِ ‏"‏ ‏.‏
Reference : Sahih Muslim 43a
In-book reference : Book 1, Hadith 72
USC-MSA web (English) reference : Book 1, Hadith 67
  (deprecated numbering scheme)