The word(s) "grievous" appears 89 time(s) in 89 verse(s) in Quran in Abdullah Yusuf Ali translation.

(11) Of no effect is the repentance of those who continue to do evil, until death faces one of them, and he says, "Now have I repented indeed;" nor of those who die rejecting Faith: for them have We prepared a punishment most grievous.

(12) To the Hypocrites give the glad tidings that there is for them (but) a grievous penalty;-

(13) That they took usury, though they were forbidden; and that they devoured men's substance wrongfully;- we have prepared for those among them who reject faith a grievous punishment.

(14) But to those who believe and do deeds of righteousness, He will give their (due) rewards,- and more, out of His bounty: But those who are disdainful and arrogant, He will punish with a grievous penalty; Nor will they find, besides Allah, any to protect or help them.

(15) As to those who reject Faith,- if they had everything on earth, and twice repeated, to give as ransom for the penalty of the Day of Judgment, it would never be accepted of them, theirs would be a grievous penalty.

(16) They do blaspheme who say: Allah is one of three in a Trinity: for there is no god except One Allah. If they desist not from their word (of blasphemy), verily a grievous penalty will befall the blasphemers among them.

(17) O ye who believe! Allah doth but make a trial of you in a little matter of game well within reach of game well within reach of your hands and your lances, that He may test who feareth him unseen: any who transgress thereafter, will have a grievous penalty.

(18) Leave alone those who take their religion to be mere play and amusement, and are deceived by the life of this world. But proclaim (to them) this (truth): that every soul delivers itself to ruin by its own acts: it will find for itself no protector or intercessor except Allah: if it offered every ransom, (or reparation), none will be accepted: such is (the end of) those who deliver themselves to ruin by their own acts: they will have for drink (only) boiling water, and for punishment, one most grievous: for they persisted in rejecting Allah.

(19) To the Thamud people (We sent) Salih, one of their own brethren: He said: "O my people! worship Allah: ye have no other god but Him. Now hath come unto you a clear (Sign) from your Lord! This she-camel of Allah is a Sign unto you: So leave her to graze in Allah's earth, and let her come to no harm, or ye shall be seized with a grievous punishment.

(20) When they disregarded the warnings that had been given them, We rescued those who forbade Evil; but We visited the wrong-doers with a grievous punishment because they were given to transgression.