Al-Abbas reported: The Messenger of Allah, peace and blessings be upon him, said, “He has tasted the sweetness of faith who is content with Allah as his Lord, Islam as his religion, and Muhammad as his Prophet.”

Source: Sahih Muslim 34

Grade: Sahih (authentic) according to Muslim

عَنِ الْعَبَّاسِ بْنِ عَبْدِ الْمُطَّلِبِ أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ذَاقَ طَعْمَ الإِيمَانِ مَنْ رَضِيَ بِاللَّهِ رَبًّا وَبِالإِسْلاَمِ دِينًا وَبِمُحَمَّدٍ رَسُولاً

34 صحيح مسلم كِتَاب الْإِيمَانِ بَاب الدَّلِيلِ عَلَى أَنَّ مَنْ رَضِيَ بِاللَّهِ رَبًّا وَبِالْإِسْلَامِ دِينًا وَبِمُحَمَّدٍ رَسُولًا فَهُوَ مُؤْمِنٌ وَإِنْ ارْتَكَبَ الْمَعَاصِيَ الْكَبَائِرَ

http://dailyhadith.abuaminaelias.com/2011/03/31/the-sweetness-of-faith-is-satisfaction-with-islam/