The word(s) "doubt" appears 60 time(s) in 58 verse(s) in Quran in Muhammad Pickthal translation.

(21) The thunder hymneth His praise and (so do) the angels for awe of Him. He launcheth the thunderbolts and smiteth with them whom He will while they dispute (in doubt) concerning Allah, and He is mighty in wrath.

(22) Hath not the history of those before you reached you: the folk of Noah, and (the tribes of) A'ad and Thamud, and those after them? None save Allah knoweth them. Their messengers came unto them with clear proofs, but they thrust their hands into their mouths, and said: Lo! we disbelieve in that wherewith ye have been sent, and lo! we are in grave doubt concerning that to which ye call us.

(23) Their messengers said: Can there be doubt concerning Allah, the Creator of the heavens and the earth? He calleth you that He may forgive you your sins and reprieve you unto an appointed term. They said: Ye are but mortals like us, who would fain turn us away from what our fathers used to worship. Then bring some clear warrant.

(24) Have they not seen that Allah Who created the heavens and the earth is Able to create the like of them, and hath appointed for them an end whereof there is no doubt? But the wrong-doers refuse aught save disbelief.

(25) And in like manner We disclosed them (to the people of the city) that they might know that the promise of Allah is true, and that, as for the Hour, there is no doubt concerning it. When (the people of the city) disputed of their case among themselves, they said: Build over them a building; their Lord knoweth best concerning them. Those who won their point said: We verily shall build a place of worship over them.

(26) Such was Jesus, son of Mary: (this is) a statement of the truth concerning which they doubt.

(27) O mankind! if ye are in doubt concerning the Resurrection, then lo! We have created you from dust, then from a drop of seed, then from a clot, then from a little lump of flesh shapely and shapeless, that We may make (it) clear for you. And We cause what We will to remain in the wombs for an appointed time, and afterward We bring you forth as infants, then (give you growth) that ye attain your full strength. And among you there is he who dieth (young), and among you there is he who is brought back to the most abject time of life, so that, after knowledge, he knoweth naught. And thou (Muhammad) seest the earth barren, but when We send down water thereon, it doth thrill and swell and put forth every lovely kind (of growth).

(28) And because the Hour will come, there is no doubt thereof; and because Allah will raise those who are in the graves.

(29) And those who disbelieve will not cease to be in doubt thereof until the Hour come upon them unawares, or there come unto them the doom of a disastrous day.

(30) Is there in their hearts a disease, or have they doubts, or fear they lest Allah and His messenger should wrong them in judgment? Nay, but such are evil-doers.