'Imran bin Husain (May Allah be pleased with them) reported:
The Prophet (ﷺ) said, "The best of you, are my contemporaries, then those who follow them, then those who will come after them. ('Imran said, I do not know if he said this twice or thrice). Then, they will be followed by those who will testify but will not be called upon to testify; they will betray the trust, and will not be trusted. They will make vows but will not fulfill them, and obesity will prevail among them."[Al-Bukhari and Muslim].
Arabic/English book reference: Book 1, Hadith 509