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

(81) And they marvel that a warner from among themselves hath come unto them, and the disbelievers say: This is a wizard, a charlatan.

(82) Say (unto them, O Muhammad): I am only a warner, and there is no Allah save Allah, the One, the Absolute,

(83) It is revealed unto me only that I may be a plain warner.

(84) And those who disbelieve are driven unto hell in troops till, when they reach it and the gates thereof are opened, and the warders thereof say unto them: Came there not unto you messengers of your own, reciting unto you the revelations of your Lord and warning you of the meeting of this your Day? they say: Yea, verily. But the word of doom of disbelievers is fulfilled.

(85) The Exalter of Ranks, the Lord of the Throne. He causeth the Spirit of His command upon whom He will of His slaves, that He may warn of the Day of Meeting,

(86) warn them (O Muhammad) of the Day of the approaching (doom), when the hearts will be choking the throats, (when) there will be no friend for the wrong-doers, nor any intercessor who will be heard.

(87) Good tidings and a warning. But most of them turn away so that they hear not.

(88) But if they turn away, then say: I warn you of a thunderbolt like the thunderbolt (which fell of old upon the tribes) of A'ad and Thamud;

(89) And thus We have inspired in thee a Lecture in Arabic, that thou mayst warn the mother-town and those around it, and mayst warn of a day of assembling whereof there is no doubt. A host will be in the Garden, and a host of them in the Flame.

(90) And even so We sent not a warner before thee (Muhammad) into any township but its luxurious ones said: Lo! we found our fathers following a religion, and we are following their footprints.