Musnad Abu Ya'la al-Mawsili 115:301

The Messenger of Allah (ﷺ) said: "There are three things, whoever possesses them will find the sweetness of faith: that a person loves another, not loving him except for the sake of Allah; and that Allah and His Messenger are more beloved to him than anything else; and that being thrown into the Fire is more beloved to him than returning to disbelief after Allah has saved him from it."