The word(s) "doubt" appears 53 time(s) in 51 verse(s) in Quran in Muhammad Habib Shakir translation.

(11) Say: To whom belongs what is in the heavens and the earth? Say: To Allah; He has ordained mercy on Himself; most certainly He will gather you on the resurrection day-- there is no doubt about it. (As for) those who have lost their souls, they will not believe.

(12) They only ask leave of you who do not believe in Allah and the latter day and their hearts are in doubt, so in their doubt do they waver.

(13) And this Quran is not such as could be forged by those besides Allah, but it is a verification of that which is before it and a clear explanation of the book, there is no doubt in it, from the Lord of the worlds.

(14) But if you are in doubt as to what We have revealed to you, ask those who read the Book before you; certainly the truth has come to you from your Lord, therefore you should not be of the disputers.

(15) Say: O people! if you are in doubt as to my religion, then (know that) I do not serve those whom you serve besides Allah but I do serve Allah, Who will cause you to die, and I am commanded that I should be of the believers.

(16) They said: O Salih! surely you were one amongst us in whom great expectations were placed before this; do you (now) forbid us from worshipping what our fathers worshipped? And as to that which you call us to, most surely we are in disquieting doubt.

(17) Therefore be not in doubt as to what these worship; they do not worship but as their fathers worshipped before; and most surely We will pay them back in full their portion undiminished.

(18) And certainly We gave the book to Musa, but it was gone against; and had not a word gone forth from your Lord, the matter would surely have been decided between them; and surely they are in a disquieting doubt about it.

(19) Has not the account reached you of those before you, of the people of Nuh and Ad and Samood, and those after them? None knows them but Allah. Their apostles come to them with clear arguments, but they thrust their hands into their mouths and said: Surely we deny that with which you are sent, and most surely we are in serious doubt as to that to which you invite us.

(20) Their apostles said: Is there doubt about Allah, the Maker of the heavens and the earth? He invites you to forgive you your faults and to respite you till an appointed term. They said: You are nothing but mortals like us; you wish to turn us away from what our fathers used to worship; bring us therefore some clear authority.