Sahih Muslim 34
Sahih Muslim · Book 1: The Book of Faith · Evidence that the one who is content with Allah as his Lord, Islam as his religion and Muhammad (saws) as his prophet, then he is a believer, even if he commits major sins
It is narrated on the authority of 'Abbas b. 'Abdul-Muttalib that he heard the Messenger of Allah saying:
حَدَّثَنَا مُحَمَّدُ بْنُ يَحْيَى بْنِ أَبِي عُمَرَ الْمَكِّيُّ ، وَبِشْرُ بْنُ الْحَكَمِ ، قَالاَ حَدَّثَنَا عَبْدُ الْعَزِيزِ، - وَهُوَ ابْنُ مُحَمَّدٍ - الدَّرَاوَرْدِيُّ عَنْ يَزِيدَ بْنِ الْهَادِ ، عَنْ مُحَمَّدِ بْنِ إِبْرَاهِيمَ ، عَنْ عَامِرِ بْنِ سَعْدٍ ، 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 "
He has found the taste of faith ( iman ) who is content with Allah as his Lord, with Islam as his religion (code of life) and with Muhammad (ﷺ) as his Prophet.