The word(s) "vain" appears 33 time(s) in 33 verse(s) in Quran in Mohsin Khan translation.

(1) O you who believe! Do not render in vain your Sadaqah (charity) by reminders of your generosity or by injury, like him who spends his wealth to be seen of men, and he does not believe in Allah, nor in the Last Day. His likeness is the likeness of a smooth rock on which is a little dust; on it falls heavy rain which leaves it bare. They are not able to do anything with what they have earned. And Allah does not guide the disbelieving people.

(2) And We have sent down to you (O Muhammad صلى الله عليه وسلم) the Book (this Qur'an) in truth, confirming the Scripture that came before it and Muhaymin (trustworthy in highness and a witness) over it (old Scriptures) . So judge among them by what Allah has revealed, and follow not their vain desires, diverging away from the truth that has come to you. To each among you, We have prescribed a law and a clear way. If Allah had willed, He would have made you one nation, but that (He) may test you in what He has given you; so compete in good deeds. The return of you (all) is to Allah; then He will inform you about that in which you used to differ.

(3) And so judge (you O Muhammad صلى الله عليه وسلم) among them by what Allah has revealed and follow not their vain desires, but beware of them lest they turn you (O Muhammad صلى الله عليه وسلم) far away from some of that which Allah has sent down to you. And if they turn away, then know that Allah's Will is to punish them for some sins of theirs. And truly, most of men are Fasiqun (rebellious and disobedient to Allah).

(4) And those who believe will say: "Are these the men (hypocrites) who swore their strongest oaths by Allah that they were with you (Muslims)?" All that they did has been in vain (because of their hypocrisy), and they have become the losers.

(5) Say (O Muhammad صلى الله عليه وسلم): "O people of the Scripture (Jews and Christians)! Exceed not the limits in your religion (by believing in something) other than the truth, and do not follow the vain desires of people who went astray before and who misled many, and strayed (themselves) from the Right Path."

(6) Say (O Muhammad صلى الله عليه وسلم): "I have been forbidden to worship those whom you invoke (worship) besides Allah." Say: "I will not follow your vain desires. If I did, I would go astray, and I would not be one of the rightly guided."

(7) They (the Jews, Quraish pagans, idolaters) did not estimate Allah with an estimation due to Him when they said: "Nothing did Allah send down to any human being (by revelation)." Say (O Muhammad صلى الله عليه وسلم): "Who then sent down the Book which Musa (Moses) brought, a light and a guidance to mankind which you (the Jews) have made into (separate) papersheets, disclosing (some of it) and concealing much. And you (believers in Allah and His Messenger Muhammad صلى الله عليه وسلم) were taught (through the Qur'an) that which neither you nor your fathers knew." Say: "Allah (sent it down)." Then leave them to play in their vain discussions. (Tafsir Al-Qurtubi).

(8) Say: "Bring forward your witnesses, who can testify that Allah has forbidden this. Then if they testify, testify not you (O Muhammad صلى الله عليه وسلم) with them. And you should not follow the vain desires of such as treat Our Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.) as falsehoods, and such as believe not in the Hereafter, and they hold others as equal (in worship) with their Lord."

(9) [Musa (Moses) added:] "Verily, these people will be destroyed for that which they are engaged in (idols-worship). And all that they are doing is in vain."

(10) Those who deny Our Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.) and the Meeting in the Hereafter (Day of Resurrection,), vain are their deeds. Are they requited with anything except what they used to do?