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

(61) And to rehearse the Qur'an: and if any accept guidance, they do it for the good of their own souls, and if any stray, say: "I am only a warner".

(62) Nor wast thou at the side of (the Mountain of) Tur when we called (to Moses). Yet (art thou sent) as Mercy from thy Lord, to give warning to a people to whom no warner had come before thee: in order that they may receive admonition.

(63) Ye they say: "Why are not Signs sent down to him from his Lord?" Say: "The signs are indeed with Allah: and I am indeed a clear warner."

(64) Or do they say, "He has forged it"? Nay, it is the Truth from thy Lord, that thou mayest admonish a people to whom no warner has come before thee: in order that they may receive guidance.

(65) O Prophet! Truly We have sent thee as a Witness, a Bearer of Glad Tidings, and warner,-

(66) We have not sent thee but as a universal (Messenger) to men, giving them glad tidings, and warning them (against sin), but most men understand not.

(67) Never did We send a warner to a population, but the wealthy ones among them said: "We believe not in the (Message) with which ye have been sent."

(68) But We had not given them Books which they could study, nor sent messengers to them before thee as warners.

(69) Say: "I do admonish you on one point: that ye do stand up before Allah,- (It may be) in pairs, or (it may be) singly,- and reflect (within yourselves): your Companion is not possessed: he is no less than a warner to you, in face of a terrible Penalty."

(70) Thou art no other than a warner.