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

(91) (And the warner) said: What! Even though I bring you better guidance than that ye found your fathers following? They answered: Lo! in what ye bring we are disbelievers.

(92) Lo! We revealed it on a blessed night - Lo! We are ever warning -

(93) We created not the heavens and the earth and all that is between them save with truth, and for a term appointed. But those who disbelieve turn away from that whereof they are warned.

(94) Say: I am no new thing among the messengers (of Allah), nor know I what will be done with me or with you. I do but follow that which is inspired in me, and I am but a plain warner.

(95) When before it there was the Scripture of Moses, an example and a mercy; and this is a confirming Scripture in the Arabic language, that it may warn those who do wrong and bring good tidings for the righteous.

(96) And make mention (O Muhammad) of the brother of A'ad when he warned his folk among the wind-curved sandhills - and verily warners came and went before and after him - saying: Serve none but Allah. Lo! I fear for you the doom of a tremendous Day.

(97) And when We inclined toward thee (Muhammad) certain of the jinn, who wished to hear the Qur'an and, when they were in its presence, said: Give ear! and, when it was finished, turned back to their people, warning.

(98) Await they aught save the Hour, that it should come upon them unawares? And the beginnings thereof have already come. But how, when it hath come upon them, can they take their warning?

(99) Lo! We have sent thee (O Muhammad) as a witness and a bearer of good tidings and a warner,

(100) Nay, but they marvel that a warner of their own hath come unto them; and the disbelievers say: This is a strange thing: