Hadith #6845 (Sahih al-Bukhari)
Book: Afflictions and the End of the World
Narrator(s): Abi Asha'sha
Grade: Sahih

Hudhaifa said, ‘In fact, it was hypocrisy that existed in the lifetime of the Prophet (ﷺ) but today it is Kufr (disbelief) after belief.’

Source: https://parallelquran.com/hadith/sahih-al-bukhari-6845/