عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " ثَلاَثٌ مَنْ كُنَّ فِيهِ وَجَدَ حَلاَوَةَ الإِيمَانِ أَنْ يَكُونَ اللَّهُ وَرَسُولُهُ أَحَبَّ إِلَيْهِ مِمَّا سِوَاهُمَا، وَأَنْ يُحِبَّ الْمَرْءَ لاَ يُحِبُّهُ إِلاَّ لِلَّهِ، وَأَنْ يَكْرَهَ أَنْ يَعُودَ فِي الْكُفْرِ كَمَا يَكْرَهُ أَنْ يُقْذَفَ فِي النَّارِ ".
Anas ibn Malik reported: The Prophet ﷺ said: “There are three things: whoever has them finds the sweetness of faith (iman): that Allah and His Messenger are dearer to him than anything besides them; that he loves a person and loves him …
also in Sahih al-Bukhari 21