The word(s) "warn" appears 150 time(s) in 135 verse(s) in Quran in Mohsin Khan translation.

(21) Say (O Muhammad صلى الله عليه وسلم): "I possess no power over benefit or harm to myself except as Allah wills. If I had the knowledge of the Ghaib (Unseen), I should have secured for myself an abundance of wealth, and no evil should have touched me. I am but a warner, and a bringer of glad tidings unto people who believe."

(22) Say to those who have disbelieved, if they cease (from disbelief), their past will be forgiven. But if they return (thereto), then the examples of those (punished) before them have already preceded (as a warning).

(23) And it is not (proper) for the believers to go out to fight (Jihad ) all together. Of every troop of them, a party only should go forth, that they (who are left behind) may get instructions in (Islamic) religion, and that they may warn their people when they return to them, so that they may beware (of evil).

(24) Is it a wonder for mankind that We have sent Our Revelation to a man from among themselves (i.e. Prophet Muhammad صلى الله عليه وسلم) (saying): "warn mankind (of the coming torment in Hell), and give good news to those who believe (in the Oneness of Allah and in His Prophet Muhammad صلى الله عليه وسلم) that they shall have with their Lord the rewards of their good deeds?" (But) the disbelievers say: "This is indeed an evident sorcerer (i.e. Prophet Muhammad صلى الله عليه وسلم and the Qur'an)!

(25) They denied him, but We delivered him, and those with him in the ship, and We made them generations replacing one after another, while We drowned those who belied Our Ayat (proofs, evidence, lessons, signs, revelations, etc.). Then see what was the end of those who were warned.

(26) Say: "Behold all that is in the heavens and the earth," but neither Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.) nor warners benefit those who believe not.

(27) (Saying) worship none but Allah. Verily, I (Muhammad صلى الله عليه و سلم) am unto you from Him a warner and a bringer of glad tidings.

(28) So perchance you (Muhammad صلى الله عليه و سلم) may give up a part of what is revealed unto you, and that your breast feels straitened for it because they say, "Why has not a treasure been sent down unto him, or an angel has come with him?" But you are only a warner. And Allah is a Wakil (Disposer of affairs, Trustee, Guardian) over all things.

(29) And indeed We sent Nuh (Noah) to his people (and he said): "I have come to you as a plain warner."

(30) And the disbelievers say: "Why is not a sign sent down to him from his Lord?" You are only a warner, and to every people there is a guide.