Al-An'am 6:25

Waminhum man yastamiAAu ilayka wajaAAalnaAAala quloobihim akinnatan an yafqahoohu wafee athanihimwaqran wa-in yaraw kulla ayatin la yu/minoo bihahatta itha jaooka yujadiloonakayaqoolu allatheena kafaroo in hatha illa asateerual-awwaleen

And among them are those who listen to you, but We have placed over their hearts coverings, lest they understand it, and in their ears deafness. And if they should see every sign, they will not believe in it. Even when they come to you arguing with you, those who disbelieve say, "This is not but legends of the former peoples."

There are those among them who (apparently) listen to you, but We have put coverings on their hearts, so that they do not understand, and heaviness in their ears. If they were to see all the signs, they would still not believe in them, so much so that, when they come to quarrel with you, the disbelievers say (of the Qur’ān), “It is nothing but tales of the ancients.”