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

(11) Say: Unto whom belongeth whatsoever is in the heavens and the earth? Say: Unto Allah. He hath prescribed for Himself mercy, that He may bring you all together to the Day of Resurrection whereof there is no doubt. Those who ruin their souls will not believe.

(12) They alone ask leave of thee who believe not in Allah and the Last Day, and whose hearts feel doubt, so in their doubt they waver.

(13) And this Qur'an is not such as could ever be invented in despite of Allah; but it is a confirmation of that which was before it and an exposition of that which is decreed for mankind - Therein is no doubt - from the Lord of the Worlds.

(14) Recite unto them the story of Noah, when he told his people: O my people! If my sojourn (here) and my reminding you by Allah's revelations are an offence unto you, in Allah have I put my trust, so decide upon your course of action you and your partners. Let not your course of action be in doubt for you. Then have at me, give me no respite.

(15) And if thou (Muhammad) art in doubt concerning that which We reveal unto thee, then question those who read the Scripture (that was) before thee. Verily the Truth from thy Lord hath come unto thee. So be not thou of the waverers.

(16) Say (O Muhammad): O mankind! If ye are in doubt of my religion, then (know that) I worship not those whom ye worship instead of Allah, but I worship Allah Who causeth you to die, and I have been commanded to be of the believers.

(17) Is he (to be counted equal with them) who relieth on a clear proof from his Lord, and a witness from Him reciteth it, and before it was the Book of Moses, an example and a mercy? Such believe therein, and whoso disbelieveth therein of the clans, the Fire is his appointed place. So be not thou in doubt concerning it. Lo! it is the Truth from thy Lord; but most of mankind believe not.

(18) They said: O Salih! Thou hast been among us hitherto as that wherein our hope was placed. Dost thou ask us not to worship what our fathers worshipped? Lo! we verily are in grave doubt concerning that to which thou callest us.

(19) So be not thou in doubt concerning that which these (folk) worship. They worship only as their fathers worshipped aforetime. Lo! we shall pay them their whole due unabated.

(20) And we verily gave unto Moses the Scripture, and there was strife thereupon; and had it not been for a Word that had already gone forth from thy Lord, the case would have been judged between them, and lo! they are in grave doubt concerning it.