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

(41) And We verily gave Moses the Scripture, but there hath been dispute concerning it; and but for a Word that had already gone forth from thy Lord, it would ere now have been judged between them; but lo! they are in hopeless doubt concerning it.

(42) How! Are they still in doubt about the meeting with their Lord? Lo! Is not He surrounding all things?

(43) And thus We have inspired in thee a Lecture in Arabic, that thou mayst warn the mother-town and those around it, and mayst warn of a day of assembling whereof there is no doubt. A host will be in the Garden, and a host of them in the Flame.

(44) And they were not divided until after the knowledge came unto them, through rivalry among themselves; and had it not been for a Word that had already gone forth from thy Lord for an appointed term, it surely had been judged between them. And those who were made to inherit the Scripture after them are verily in hopeless doubt concerning it.

(45) Those who believe not therein seek to hasten it, while those who believe are fearful of it and know that it is the Truth. Are not they who dispute, in doubt concerning the Hour, far astray?

(46) And lo! verily there is knowledge of the Hour. So doubt ye not concerning it, but follow Me. This is the right path.

(47) Nay, but they play in doubt.

(48) Lo! this is that whereof ye used to doubt.

(49) Say (unto them, O Muhammad): Allah giveth life to you, then causeth you to die, then gathereth you unto the Day of Resurrection whereof there is no doubt. But most of mankind know not.

(50) And when it was said: Lo! Allah's promise is the truth, and there is no doubt of the Hour's coming, ye said: We know not what the Hour is. We deem it naught but a conjecture, and we are by no means convinced.