Hadithcore
Hadith #2312810
sahih· Al-Albani

Abu Hurayra related, "Some people said, 'Messenger of Allah, we feel in ourselves something which we do not want to speak about and we have been in that state since sunrise.' He said, 'Have you really felt like that?' 'Yes,' they said. He said, 'That is clear belief.'"

حَدَّثَنَا مُحَمَّدُ بْنُ سَلاَمٍ، قَالَ‏:‏ أَخْبَرَنَا عَبْدَةُ، عَنْ مُحَمَّدِ بْنِ عَمْرٍو، قَالَ‏:‏ حَدَّثَنَا أَبُو سَلَمَةَ، عَنْ أَبِي هُرَيْرَةَ‏:‏ قَالُوا‏:‏ يَا رَسُولَ اللهِ، إِنَّا نَجِدُ فِي أَنْفُسِنَا شَيْئًا مَا نُحِبُّ أَنْ نَتَكَلَّمَ بِهِ وَإِنَّ لَنَا مَا طَلَعَتْ عَلَيْهِ الشَّمْسُ، قَالَ‏:‏ أَوَ قَدْ وَجَدْتُمْ ذَلِكَ‏؟‏ قَالُوا‏:‏ نَعَمْ، قَالَ‏:‏ ذَاكَ صَرِيحُ الإيمَانِ‏.‏

References2 variants
Sunnah.com reference
Book 55, Hadith 3
Arabic/English book reference
Book 55, Hadith 1284