Sahih al-Bukhari 7114

Arabic

حَدَّثَنَا خَلاَّدٌ، حَدَّثَنَا مِسْعَرٌ، عَنْ حَبِيبِ بْنِ أَبِي ثَابِتٍ، عَنْ أَبِي الشَّعْثَاءِ، عَنْ حُذَيْفَةَ، قَالَ إِنَّمَا كَانَ النِّفَاقُ عَلَى عَهْدِ النَّبِيِّ صلى الله عليه وسلم فَأَمَّا الْيَوْمَ فَإِنَّمَا هُوَ الْكُفْرُ بَعْدَ الإِيمَانِ‏.‏

English translation

Narrated Abi Asha'sha:Hudhaifa said, 'In fact, it was hypocrisy that existed in the lifetime of the Prophet (ﷺ) but today it is Kufr (disbelief) after belief

Reference: Sahih al-Bukhari 7114, Book of Afflictions and the End of the World. English translation by Dr. Muhammad Muhsin Khan.