that he heard the Messenger of Allah (ﷺ) say: "Whoever is pleased with Allah as (his) Lord, and Islam as (his) religion, and Muhammad as (his) Prophet, then he has tasted the sweetness of faith."
Jami` at-Tirmidhi Book 40, Hadith 18
← Previous Hadith The Companions of Muhammad (ﷺ) didn't consider leaving anything to be disblief except for the Salat.

Jami` at-Tirmidhi Book 40, Hadith 17 Next Hadith → that the Messenger of Allah (ﷺ) said: "There are three things for which whomever has them, then he has tasted the sweetness of faith: The one for whom Allah and His Messenger are more beloved than anything else; whoever loves someone and he does not love him except for the sake of Allah, and whoever hates to return to disbelief after Allah has saved him from it, just as he hates to be thrown into fire."

Jami` at-Tirmidhi Book 40, Hadith 19