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

(11) O ye assembly of the jinn and humankind! Came there not unto you messengers of your own who recounted unto you My tokens and warned you of the meeting of this your Day? They will say: We testify against ourselves. And the life of the world beguiled them. And they testify against themselves that they were disbelievers.

(12) (It is) a Scripture that is revealed unto thee (Muhammad) - so let there be no heaviness in thy heart therefrom - that thou mayst warn thereby, and (it is) a Reminder unto believers.

(13) Marvel ye that there should come unto you a Reminder from your Lord by means of a man among you, that he may warn you, and that ye may keep from evil, and that haply ye may find mercy.

(14) Marvel ye that there should come unto you a Reminder from your Lord by means of a man among you, that he may warn you? Remember how He made you viceroys after Noah's folk, and gave you growth of stature. Remember (all) the bounties of your Lord, that haply ye may be successful.

(15) Have they not bethought them (that) there is no madness in their comrade? He is but a plain warner.

(16) Say: For myself I have no power to benefit, nor power to hurt, save that which Allah willeth. Had I knowledge of the Unseen, I should have abundance of wealth, and adversity would not touch me. I am but a warner, and a bearer of good tidings unto folk who believe.

(17) Tell those who disbelieve that if they cease (from persecution of believers) that which is past will be forgiven them; but if they return (thereto) then the example of the men of old hath already gone (before them, for a warning).

(18) And the believers should not all go out to fight. Of every troop of them, a party only should go forth, that they (who are left behind) may gain sound knowledge in religion, and that they may warn their folk when they return to them, so that they may beware.

(19) Is it a wonder for mankind that We have inspired a man among them, saying: warn mankind and bring unto those who believe the good tidings that they have a sure footing with their Lord? The disbelievers say: Lo! this is a mere wizard.

(20) But they denied him, so We saved him and those with him in the ship, and made them viceroys (in the earth), while We drowned those who denied Our revelations. See then the nature of the consequence for those who had been warned.