The Messenger of Allah (peace and blessings of Allah be upon him) said:

“There are three things which if a person finds them, he has found the sweetness of faith: when Allah and His Messenger are dearer to him than all else; when he loves a person for no other reason than for the sake of Allah; and when he hates to return to kufr after Allah has saved him from it as he would hate to be thrown into fire.” (Narrated from the hadith of Anas ibn Malik)

Sahih al-Bukhari 16