It was narrated from Anas that :The Prophet [SAW] said: "There are three things, whoever attains them will find therein the sweetness of Islam: When Allah [SWT] and His Messenger [SAW] are dearer to him than all else; when he loves a person and only loves him for the sake of Allah [SWT]; and when he would hate to go back to disbelief as much as he would hate to be thrown into the fire."
أَخْبَرَنَا عَلِيُّ بْنُ حُجْرٍ، قَالَ حَدَّثَنَا إِسْمَاعِيلُ، عَنْ حُمَيْدٍ، عَنْ أَنَسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " ثَلاَثٌ مَنْ كُنَّ فِيهِ وَجَدَ بِهِنَّ حَلاَوَةَ الإِسْلاَمِ مَنْ كَانَ اللَّهُ وَرَسُولُهُ أَحَبَّ إِلَيْهِ مِمَّا سِوَاهُمَا وَمَنْ أَحَبَّ الْمَرْءَ لاَ يُحِبُّهُ إِلاَّ لِلَّهِ وَمَنْ يَكْرَهُ أَنْ يَرْجِعَ إِلَى الْكُفْرِ كَمَا يَكْرَهُ أَنْ يُلْقَى فِي النَّارِ " .
Nesai
The Book Of Faith and its Signs • Hadith 4989