The word(s) "warn" appears 147 time(s) in 131 verse(s) in Quran in Muhammad Pickthal translation.

(1) As for the Disbelievers, Whether thou warn them or thou warn them not it is all one for them; they believe not.

(2) Lo! We have sent thee (O Muhammad) with the truth, a bringer of glad tidings and a warner. And thou wilt not be asked about the owners of hell-fire.

(3) Mankind were one community, and Allah sent (unto them) prophets as bearers of good tidings and as warners, and revealed therewith the Scripture with the truth that it might judge between mankind concerning that wherein they differed. And only those unto whom (the Scripture) was given differed concerning it, after clear proofs had come unto them, through hatred one of another. And Allah by His Will guided those who believe unto the truth of that concerning which they differed. Allah guideth whom He will unto a straight path.

(4) And if ye do not, then be warned of war (against you) from Allah and His messenger. And if ye repent, then ye have your principal (without interest). Wrong not, and ye shall not be wronged.

(5) Messengers of good cheer and of warning, in order that mankind might have no argument against Allah after the messengers. Allah was ever Mighty, Wise.

(6) O People of the Scripture! Now hath Our messenger come unto you to make things plain unto you after an interval (of cessation) of the messengers, lest ye should say: There came not unto us a messenger of cheer nor any warner. Now hath a messenger of cheer and a warner come unto you. Allah is Able to do all things.

(7) Say (O Muhammad): What thing is of most weight in testimony? Say: Allah is Witness between me and you. And this Qur'an hath been inspired in me, that I may warn therewith you and whomsoever it may reach. Do ye in sooth bear witness that there are gods beside Allah? Say: I bear no such witness. Say: He is only One Allah. Lo! I am innocent of that which ye associate (with Him).

(8) We send not the messengers save as bearers of good news and warners. Whoso believeth and doeth right, there shall no fear come upon them neither shall they grieve.

(9) warn hereby those who fear (because they know) that they will be gathered unto their Lord, for whom there is no protecting ally nor intercessor beside Him, that they may ward off (evil).

(10) And this is a blessed Scripture which We have revealed, confirming that which (was revealed) before it, that thou mayst warn the Mother of Villages and those around her. Those who believe in the Hereafter believe herein, and they are careful of their worship.