The word(s) "certainty" appears 23 time(s) in 23 verse(s) in Quran in Mohsin Khan translation.

(21) And verily, it (this Qur'an) is an absolute truth with certainty.

(22) And We have set none but angels as guardians of the Fire. And We have fixed their number (19) only as a trial for the disbelievers, in order that the people of the Scripture (Jews and Christians) may arrive at a certainty [that this Qur'an is the truth as it agrees with their Books regarding the number (19) which is written in the Taurat (Torah) and the Injeel (Gospel)] and that the believers may increase in Faith (as this Qur'an is the truth), and that no doubt may be left for the people of the Scripture and the believers, and that those in whose hearts is a disease (of hypocrisy) and the disbelievers may say: "What Allah intends by this (curious) example ?" Thus Allah leads astray whom He wills and guides whom He wills. And none can know the hosts of your Lord but He. And this (Hell) is nothing else than a (warning) reminder to mankind.

(23) And again, you shall see it with certainty of sight!