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

(121) "Then taste you My Torment and My warnings."

(122) And indeed, warnings came to the people of Fir'aun (Pharaoh) [through Musa (Moses) and Harun (Aaron)].

(123) It almost bursts up with fury. Every time a group is cast therein, its keeper will ask: "Did no warner come to you?"

(124) They will say: "Yes, indeed a warner did come to us, but we belied him and said: 'Allah never sent down anything (of revelation); you are only in great error.'"

(125) Or do you feel secure that He, Who is over the heaven (Allah), will not send against you a violent whirlwind? Then you shall know how (terrible) has been My warning.

(126) Say (O Muhammad صلى الله عليه وسلم): "The knowledge (of its exact time) is with Allah only, and I am only a plain warner."

(127) Verily, We sent Nuh (Noah) to his people (saying): "warn your people before there comes to them a painful torment."

(128) He said: "O my people! Verily, I am a plain warner to you,

(129) Arise and warn!

(130) And We have set none but angels as guardians of the Fire. And We have fixed their number (19) only as a trial for the disbelievers, in order that the people of the Scripture (Jews and Christians) may arrive at a certainty [that this Qur'an is the truth as it agrees with their Books regarding the number (19) which is written in the Taurat (Torah) and the Injeel (Gospel)] and that the believers may increase in Faith (as this Qur'an is the truth), and that no doubt may be left for the people of the Scripture and the believers, and that those in whose hearts is a disease (of hypocrisy) and the disbelievers may say: "What Allah intends by this (curious) example ?" Thus Allah leads astray whom He wills and guides whom He wills. And none can know the hosts of your Lord but He. And this (Hell) is nothing else than a (warning) reminder to mankind.