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

(61) We will, without doubt, help our messengers and those who believe, (both) in this world's life and on the Day when the Witnesses will stand forth,-

(62) The Hour will certainly come: Therein is no doubt: Yet most men believe not.

(63) We certainly gave Moses the Book aforetime: but disputes arose therein. Had it not been for a Word that went forth before from thy Lord, (their differences) would have been settled between them: but they remained in suspicious disquieting doubt thereon.

(64) Ah indeed! Are they in doubt concerning the Meeting with their Lord? Ah indeed! It is He that doth encompass all things!

(65) Thus have We sent by inspiration to thee an Arabic Qur'an: that thou mayest warn the Mother of Cities and all around her,- and warn (them) of the Day of Assembly, of which there is no doubt: (when) some will be in the Garden, and some in the Blazing Fire.

(66) And they became divided only after Knowledge reached them,- through selfish envy as between themselves. Had it not been for a Word that went forth before from thy Lord, (tending) to a Term appointed, the matter would have been settled between them: But truly those who have inherited the Book after them are in suspicious (disquieting) doubt concerning it.

(67) And (Jesus) shall be a Sign (for the coming of) the Hour (of Judgment): therefore have no doubt about the (Hour), but follow ye Me: this is a Straight Way.

(68) Yet they play about in doubt.

(69) "Truly this is what ye used to doubt!"

(70) Say: "It is Allah Who gives you life, then gives you death; then He will gather you together for the Day of Judgment about which there is no doubt": But most men do not understand.