From Sahih Bukhari (Hadith 3650):
Narrated `Imran bin Husain:"Allah's Messenger (ﷺ) said, 'The best of my followers are those living in my generation (i.e. my contemporaries). and then those who will follow the latter" `Imran added, "I do not remember whether he mentioned two or three generations after his generation, then the Prophet (ﷺ) added, 'There will come after you, people who will bear witness without being asked to do so, and will be treacherous and untrustworthy, and they will vow and never fulfill their vows, and fatness will appear among them
Reference: Bukhari 3650