Mishkat al-Masabih 8
He also reported God’s messenger as saying, “There are three qualities for which anyone who is characterised by them will experience the sweetness of faith:
he to whom God and His messenger are dearer than all else; he who loves a human being for God’s sake alone; and he who has as great an abhorrence of returning to unbelief after God has rescued him from it as he has of being cast into hell.” 

(Bukhari and Muslim.)
وَعَنْ أَنَسٍ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ 
" ثَلَاثٌ مَنْ كُنَّ فِيهِ وَجَدَ بِهِنَّ حَلَاوَةَ الْإِيمَانِ: مَنْ كَانَ اللَّهُ وَرَسُولُهُ أَحَبَّ إِلَيْهِ مِمَّا سِوَاهُمَا وَمَنْ أَحَبَّ عَبْدًا لَا يُحِبُّهُ إِلَّا لِلَّهِ وَمَنْ يَكْرَهُ أَنْ يَعُودَ فِي الْكُفْرِ بَعْدَ أَنْ أَنْقَذَهُ اللَّهُ مِنْهُ كَمَا يكره أَن يلقى فِي النَّار "