Quran 2:170 from Surah Al-Baqara on Divine Marvels.
وَإِذَا قِيلَ لَهُمُ ٱتَّبِعُواْ مَآ أَنزَلَ ٱللَّهُ قَالُواْ بَلۡ نَتَّبِعُ مَآ أَلۡفَيۡنَا عَلَيۡهِ ءَابَآءَنَآۚ أَوَلَوۡ كَانَ ءَابَآؤُهُمۡ لَا يَعۡقِلُونَ شَيۡـٔٗا وَلَا يَهۡتَدُونَ
English translation: And when it is said to them Follow what has revealed Allah they said Nay we follow what we found [on it] our forefathers (following) Even though [were] their forefathers (did) not understand anything and not were they guided
Transliteration: wa-idha qila lahumu ittabi'u ma anzala al-lahu qalu bal nattabi'u ma alfayna alayhi abaana awalaw kana abauhum la ya'qiluna shayan wala yahtaduna