al-Bukhārī in his Sahīh, on the authority of Abū Hurayra, that the Prophet, may Allah bless him and grant him peace, said:

“The Hour will not come until my community follows the ways of earlier generations, span by span and cubit by cubit.” He was asked: “O Messenger of Allah, do you mean the Persians and the Romans?” He replied: “Who else but they?”