The word(s) "warn" appears 140 time(s) in 128 verse(s) in Quran in Abdullah Yusuf Ali translation.

(71) Verily We have sent thee in truth, as a bearer of glad tidings, and as a warner: and there never was a people, without a warner having lived among them (in the past).

(72) Therein will they cry aloud (for assistance): "Our Lord! Bring us out: we shall work righteousness, not the (deeds) we used to do!" - "Did We not give you long enough life so that he that would should receive admonition? and (moreover) the warner came to you. So taste ye (the fruits of your deeds): for the wrong-doers there is no helper."

(73) They swore their strongest oaths by Allah that if a warner came to them, they would follow his guidance better than any (other) of the Peoples: But when a warner came to them, it has only increased their flight (from righteousness),-

(74) "This is the Hell of which ye were (repeatedly) warned!

(75) But when it descends into the open space before them, evil will be the morning for those who were warned (and heeded not)!

(76) So they wonder that a warner has come to them from among themselves! and the Unbelievers say, "This is a sorcerer telling lies!

(77) Say: "Truly am I a warner: no god is there but the one Allah, Supreme and Irresistible,-

(78) 'Only this has been revealed to me: that I am to give warning plainly and publicly."

(79) They shall have Layers of Fire above them, and Layers (of Fire) below them: with this doth Allah warn off his servants: "O My Servants! then fear ye Me!"

(80) The Unbelievers will be led to Hell in crowd: until, when they arrive, there, its gates will be opened. And its keepers will say, "Did not messengers come to you from among yourselves, rehearsing to you the Signs of your Lord, and warning you of the Meeting of This Day of yours?" The answer will be: "True: but the Decree of Punishment has been proved true against the Unbelievers!"