The word(s) "doubt" appears 83 time(s) in 78 verse(s) in Quran in Abdullah Yusuf Ali translation.

(71) "And when it was said that the promise of Allah was true, and that the Hour- there was no doubt about its (coming), ye used to say, 'We know not what is the hour: we only think it is an idea, and we have no firm assurance.'"

(72) Only those are Believers who have believed in Allah and His Messenger, and have never since doubted, but have striven with their belongings and their persons in the Cause of Allah: Such are the sincere ones.

(73) Were We then weary with the first Creation, that they should be in confused doubt about a new Creation?

(74) "Who forbade what was good, transgressed all bounds, cast doubts and suspicions;

(75) (Those without) will call out, "Were we not with you?" (The others) will reply, "True! but ye led yourselves into temptation; ye looked forward (to our ruin); ye doubted (Allah's Promise); and (your false) desires deceived you; until there issued the Command of Allah. And the Deceiver deceived you in respect of Allah.

(76) Such of your women as have passed the age of monthly courses, for them the prescribed period, if ye have any doubts, is three months, and for those who have no courses (it is the same): for those who carry (life within their wombs), their period is until they deliver their burdens: and for those who fear Allah, He will make their path easy.

(77) And We have set none but angels as Guardians of the Fire; and We have fixed their number only as a trial for Unbelievers,- in order that the People of the Book may arrive at certainty, and the Believers may increase in Faith,- and that no doubts may be left for the People of the Book and the Believers, and that those in whose hearts is a disease and the Unbelievers may say, "What symbol doth Allah intend by this?" Thus doth Allah leave to stray whom He pleaseth, and guide whom He pleaseth: and none can know the forces of thy Lord, except He and this is no other than a warning to mankind.

(78) And without doubt he saw him in the clear horizon.