From Sahih Bukhari (Hadith 7320):
Narrated Abu Sa`id Al-Khudri:The Prophet (ﷺ) said, "You will follow the ways of those nations who were before you, span by span and cubit by cubit (i.e., inch by inch) so much so that even if they entered a hole of a mastigure, you would follow them." We said, "O Allah's Messenger (ﷺ)! (Do you mean) the Jews and the Christians?" He said, "Whom else?
Reference: Bukhari 7320