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

(71) And We had not given them Scriptures which they could study, nor sent to them before you (O Muhammad صلى الله عليه وسلم) any warner (Messenger).

(72) Say (to them O Muhammad صلى الله عليه وسلم): "I exhort you to one (thing) only: that you stand up for Allah's sake in pairs and singly, and reflect (within yourselves the life history of the Prophet صلى الله عليه وسلم): there is no madness in your companion (Muhammad صلى الله عليه وسلم). He is only a warner to you in face of a severe torment."

(73) And no bearer of burdens shall bear another's burden; and if one heavily laden calls another to (bear) his load, nothing of it will be lifted even though he be near of kin. You (O Muhammad صلى الله عليه وسلم) can warn only those who fear their Lord unseen and perform As-Salat (Iqamat-as-Salat). And he who purifies himself (from all kinds of sins), then he purifies only for the benefit of his ownself. And to Allah is the (final) Return (of all).

(74) You (O Muhammad صلى الله عليه وسلم) are only a warner (i.e. your duty is to convey Allah's Message to mankind but the guidance is Allah's).

(75) Verily We have sent you with the truth, a bearer of glad tidings and a warner. And there never was a nation but a warner had passed among them.

(76) Therein they will cry: "Our Lord! Bring us out, we shall do righteous good deeds, not (the evil deeds) that we used to do." (Allah will reply): "Did We not give you lives long enough, so that whosoever would receive admonition could receive it? And the warner came to you. So taste you (the evil of your deeds). For the Zalimun (polytheists and wrong-doers) there is no helper."

(77) And they swore by Allah their most binding oath that if a warner came to them, they would be more guided than any of the nations (before them); yet when a warner (Muhammad صلى الله عليه وسلم) came to them, it increased in them nothing but flight (from the truth)

(78) In order that you may warn a people whose forefathers were not warned, so they are heedless.

(79) It is the same to them whether you warn them or you warn them not, they will not believe.

(80) You can only warn him who follows the Reminder (the Qur'an), and fears the Most Gracious (Allah) unseen. Bear you to such one the glad tidings of forgiveness, and a generous reward (i.e. Paradise).