The word(s) "certainly" appears 150 time(s) in 144 verse(s) in Quran in Mohsin Khan translation.

(81) So think not that Allah will fail to keep His Promise to His Messengers. certainly, Allah is All-Mighty, All-Able of Retribution.

(82) And certainly We! We it is Who give life, and cause death, and We are the Inheritors.

(83) "certainly, you shall have no authority over My slaves, except those who follow you of the Ghawun (Mushrikun and those who go astray, criminals, polytheists, and evil-doers).

(84) "And we have brought you the truth (the news of the destruction of your nation) and certainly, we tell the truth.

(85) So, by your Lord (O Muhammad صلى الله عليه و سلم), We shall certainly call all of them to account.

(86) certainly, Allah knows what they conceal and what they reveal. Truly, He likes not the proud.

(87) And as for those who emigrated for the Cause of Allah, after they had been wronged, We will certainly give them goodly residence in this world, but indeed the reward of the Hereafter will be greater; if they but knew!

(88) And they assign a portion of that which We have provided them unto what they know not (false deities). By Allah, you shall certainly be questioned about (all) that you used to fabricate.

(89) He hides himself from the people because of the evil of that whereof he has been informed. Shall he keep her with dishonour or bury her in the earth ? certainly, evil is their decision.

(90) And be not like her who undoes the thread which she has spun, after it has become strong, by taking your oaths as a means of deception among yourselves, lest a nation should be more numerous than another nation. Allah only tests you by this [i.e who obeys Allah and fulfils Allah's Covenant and who disobeys Allah and breaks Allah's Covenant]. And on the Day of Resurrection, He will certainly make clear to you that wherein you used to differ [i.e. a believer confesses and believes in the Oneness of Allah and in the Prophethood of Prophet Muhammad صلى الله عليه و سلم which the disbeliever denies and that is their difference amongst them in the life of this world] .