Musnad Abu Ya'la al-Mawsili 115:159

Muhammad ibn al-Muthanna narrated to us, Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, he said: And I heard Qatadah narrating from Anas, he said: The Messenger of Allah (may Allah bless him and grant him peace) said: "Three things, whoever possesses them will find the sweetness of faith: [the one] who loves a person, not loving him except for the sake of Allah; and [the one] for whom Allah and His Messenger are more beloved to him than anything else besides them; and [the one] for whom being cast into the Fire is more beloved to him than returning to disbelief after Allah has saved him from it."