The word(s) "foolish" appears 8 time(s) in 7 verse(s) in Quran in Saheeh International translation.

(1) And when it is said to them, "Believe as the people have believed," they say, "Should we believe as the foolish have believed?" Unquestionably, it is they who are the foolish, but they know [it] not.

(2) The foolish among the people will say, "What has turned them away from their qiblah, which they used to face?" Say, "To Allah belongs the east and the west. He guides whom He wills to a straight path."

(3) Those will have lost who killed their children in foolishness without knowledge and prohibited what Allah had provided for them, inventing untruth about Allah. They have gone astray and were not [rightly] guided.

(4) Said the eminent ones who disbelieved among his people, "Indeed, we see you in foolishness, and indeed, we think you are of the liars."

(5) [Hud] said, "O my people, there is not foolishness in me, but I am a messenger from the Lord of the worlds."

(6) And Moses chose from his people seventy men for Our appointment. And when the earthquake seized them, he said, "My Lord, if You had willed, You could have destroyed them before and me [as well]. Would You destroy us for what the foolish among us have done? This is not but Your trial by which You send astray whom You will and guide whom You will. You are our Protector, so forgive us and have mercy upon us; and You are the best of forgivers.

(7) And that our foolish one has been saying about Allah an excessive transgression.