The word(s) "certain" appears 144 time(s) in 135 verse(s) in Quran in Abdullah Yusuf Ali translation.

(121) And had it not been that Allah had decreed banishment for them, He would certainly have punished them in this world: And in the Hereafter they shall (certainly) have the Punishment of the Fire.

(122) O ye who believe! When there come to you believing women refugees, examine (and test) them: Allah knows best as to their Faith: if ye ascertain that they are Believers, then send them not back to the Unbelievers. They are not lawful (wives) for the Unbelievers, nor are the (Unbelievers) lawful (husbands) for them. But pay the Unbelievers what they have spent (on their dower), and there will be no blame on you if ye marry them on payment of their dower to them. But hold not to the guardianship of unbelieving women: ask for what ye have spent on their dowers, and let the (Unbelievers) ask for what they have spent (on the dowers of women who come over to you). Such is the command of Allah: He judges (with justice) between you. And Allah is Full of Knowledge and Wisdom.

(123) And whether ye hide your word or publish it, He certainly has (full) knowledge, of the secrets of (all) hearts.

(124) We should certainly seize him by his right hand,

(125) And We should certainly then cut off the artery of his heart:

(126) And We certainly know that there are amongst you those that reject (it).

(127) But verily it is Truth of assured certainty.

(128) Now I do call to witness the Lord of all points in the East and the West that We can certainly-

(129) (And Allah's Message is): "If they (the Pagans) had (only) remained on the (right) Way, We should certainly have bestowed on them Rain in abundance.

(130) 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.