The Quran

وَكَذٰلِكَ ما أَرسَلنا مِن قَبلِكَ في قَريَةٍ مِن نَذيرٍ إِلّا قالَ مُترَفوها إِنّا وَجَدنا آباءَنا عَلىٰ أُمَّةٍ وَإِنّا عَلىٰ آثارِهِم مُقتَدونَ

Muhammad Asad

And thus it is: whenever We sent, before thy time, a warner to any community, those of its people who had lost themselves entirely in the pursuit of pleasures¹ would always say, "Behold, we found our forefathers agreed on what to believe - and, verily, it is but in their footsteps that we follow!"²

For this rendering of the term mutraf (derived from the verb tarafa), see note 147 on 11:116.
Commenting on this passage, Razi says: "Had there been in the Qur'an nothing but these verses, they would have sufficed to show the falsity of the principle postulating [a Muslim's] blind, unquestioning adoption of [another person's] religious opinions (ibtal al-qawl bi't-taqlid): for, God has made it clear [in these verses] that those deniers of the truth had not arrived at their convictions by way of reason, and neither on the clear authority of a revealed text, but solely by blindly adopting the opinions of their forebears and predecessors; and all this God has mentioned in terms of blame and sharp disparagement."