Sahih Muslim Book - 1, Hadith - 165

حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ وَمُحَمَّدُ بْنُ يَحْيَى بْنِ أَبِي عُمَرَ وَمُحَمَّدُ بْنُ بَشَّارٍ جَمِيعًا عَنْ الثَّقَفِيِّ قَالَ ابْنُ أَبِي عُمَرَ حَدَّثَنَا عَبْدُ الْوَهَّابِ عَنْ أَيُّوبَ عَنْ أَبِي قِلَابَةَ عَنْ أَنَسٍ عَنْ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ ثَلَاثٌ مَنْ كُنَّ فِيهِ وَجَدَ بِهِنَّ حَلَاوَةَ الْإِيمَانِ مَنْ كَانَ اللَّهُ وَرَسُولُهُ أَحَبَّ إِلَيْهِ مِمَّا سِوَاهُمَا وَأَنْ يُحِبَّ الْمَرْءَ لَا يُحِبُّهُ إِلَّا لِلَّهِ وَأَنْ يَكْرَهَ أَنْ يَعُودَ فِي الْكُفْرِ بَعْدَ أَنْ أَنْقَذَهُ اللَّهُ مِنْهُ كَمَا يَكْرَهُ أَنْ يُقْذَفَ فِي النَّارِ.

It was narrated from Anas that the Prophet (s.a.w) said: "There are three characteristics, whoever attains them has found the sweetness of faith: When Allah and His Messenger are dearer to him than others than them, when he loves a man and does not love him except for the sake of Allah, and when he would hate to return to disbelief after Allah has saved him from it, as he would hate to be thrown into the fire."