The word(s) "truthful" appears 63 time(s) in 62 verse(s) in Quran in Muhammad Habib Shakir translation.

(31) And they say: When will this threat come to pass if you are truthful?

(32) And (as for) those who accuse their wives and have no witnesses except themselves, the evidence of one of these (should be taken) four times, bearing Allah to witness that he is most surely of the truthful ones.

(33) And the fifth (time) that the wrath of Allah be on her if he is one of the truthful.

(34) Said he: Bring it then, if you are of the truthful ones.

(35) You are naught but a mortal like ourselves; so bring a sign if you are one of the truthful.

(36) Therefore cause a portion of the heaven to come down upon us, if you are one of the truthful.

(37) They said: Swear to each other by Allah that we will certainly make a sudden attack on him and his family by night, then we will say to his heir: We did not witness the destruction of his family, and we are most surely truthful.

(38) Or, Who originates the creation, then reproduces it and Who gives you sustenance from the heaven and the earth. Is there a god With Allah? Say: Bring your proof if you are truthful.

(39) And they say: When will this threat come to pass, if you are truthful?

(40) Say: Then bring some (other) book from Allah which is a better guide than both of them, (that) I may follow it, if you are truthful.