The word(s) "certain" appears 25 time(s) in 25 verse(s) in Quran in Muhammad Pickthal translation.

(21) And when We inclined toward thee (Muhammad) certain of the jinn, who wished to hear the Qur'an and, when they were in its presence, said: Give ear! and, when it was finished, turned back to their people, warning.

(22) Lo! this is certain truth.

(23) Till (the day) when they shall behold that which they are promised (they may doubt); but then they will know (for certain) who is weaker in allies and less in multitude.

(24) Lo! the vigil of the night is (a time) when impression is more keen and speech more certain.

(25) We have appointed only angels to be wardens of the Fire, and their number have We made to be a stumbling-block for those who disbelieve; that those to whom the Scripture hath been given may have certainty, and that believers may increase in faith; and that those to whom the Scripture hath been given and believers may not doubt; and that those in whose hearts there is disease, and disbelievers, may say: What meaneth Allah by this similitude? Thus Allah sendeth astray whom He will, and whom He will He guideth. None knoweth the hosts of thy Lord save Him. This is naught else than a Reminder unto mortals.