Abu Sa'id al-Khudri reported Allah's Messenger (ﷺ) as saying: You would tread the same path as was trodden by those before you inch by inch and step by step so much so that if they had entered into the hole of the lizard, you would follow them in this also. We said: Allah's Messenger, do you mean Jews and Christians (by your words)" those before you"? He said: Who else (than those two religious groups)?
Source: sunnah.com
Other translations
Arabic
حَدَّثَنِي سُوَيْدُ بْنُ سَعِيدٍ، حَدَّثَنَا حَفْصُ بْنُ مَيْسَرَةَ، حَدَّثَنِي زَيْدُ بْنُ أَسْلَمَ، عَنْ عَطَاءِ، بْنِ يَسَارٍ عَنْ أَبِي سَعِيدٍ الْخُدْرِيِّ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لَتَتَّبِعُنَّ سَنَنَ الَّذِينَ مِنْ قَبْلِكُمْ شِبْرًا بِشِبْرٍ وَذِرَاعًا بِذِرَاعٍ حَتَّى لَوْ دَخَلُوا فِي جُحْرِ ضَبٍّ لاَتَّبَعْتُمُوهُمْ " . قُلْنَا يَا رَسُولَ اللَّهِ آلْيَهُودَ وَالنَّصَارَى قَالَ " فَمَنْ " .
sunnah.com