The word(s) "foolish" appears 12 time(s) in 11 verse(s) in Quran in Muhammad Pickthal translation.

(1) And when it is said unto them: believe as the people believe, they say: shall we believe as the foolish believe? are not they indeed the foolish? But they know not.

(2) And when Moses said unto his people: Lo! Allah commandeth you that ye sacrifice a cow, they said: Dost thou make game of us? He answered: Allah forbid that I should be among the foolish!

(3) The foolish of the people will say: What hath turned them from the qiblah which they formerly observed? Say: Unto Allah belong the East and the West. He guideth whom He will unto a straight path.

(4) Give not unto the foolish (what is in) your (keeping of their) wealth, which Allah hath given you to maintain; but feed and clothe them from it, and speak kindly unto them.

(5) And if their aversion is grievous unto thee, then, if thou canst, seek a way down into the earth or a ladder unto the sky that thou mayst bring unto them a portent (to convince them all)! - If Allah willed, He could have brought them all together to the guidance - So be not thou among the foolish ones.

(6) The chieftains of his people, who were disbelieving, said: Lo! we surely see thee in foolishness, and lo! we deem thee of the liars.

(7) He said: O my people! There is no foolishness in me, but I am a messenger from the Lord of the Worlds.

(8) He said: O my Lord! Prison is more dear than that unto which they urge me, and if Thou fend not off their wiles from me I shall incline unto them and become of the foolish.

(9) The (faithful) slaves of the Beneficent are they who walk upon the earth modestly, and when the foolish ones address them answer: Peace;

(10) What aileth you? How foolishly ye judge!