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

(21) Behold! thy Lord did declare that He would send against them, to the Day of Judgment, those who would afflict them with grievous penalty. Thy Lord is quick in retribution, but He is also Oft-forgiving, Most Merciful.

(22) Remember how they said: "O Allah if this is indeed the Truth from Thee, rain down on us a shower of stones form the sky, or send us a grievous penalty."

(23) And an announcement from Allah and His Messenger, to the people (assembled) on the day of the Great Pilgrimage,- that Allah and His Messenger dissolve (treaty) obligations with the Pagans. If then, ye repent, it were best for you; but if ye turn away, know ye that ye cannot frustrate Allah. And proclaim a grievous penalty to those who reject Faith.

(24) O ye who believe! there are indeed many among the priests and anchorites, who in Falsehood devour the substance of men and hinder (them) from the way of Allah. And there are those who bury gold and silver and spend it not in the way of Allah: announce unto them a most grievous penalty-

(25) Unless ye go forth, He will punish you with a grievous penalty, and put others in your place; but Him ye would not harm in the least. For Allah hath power over all things.

(26) Among them are men who molest the Prophet and say, "He is (all) ear." Say, "He listens to what is best for you: he believes in Allah, has faith in the Believers, and is a Mercy to those of you who believe." But those who molest the Messenger will have a grievous penalty.

(27) They swear by Allah that they said nothing (evil), but indeed they uttered blasphemy, and they did it after accepting Islam; and they meditated a plot which they were unable to carry out: this revenge of theirs was (their) only return for the bounty with which Allah and His Messenger had enriched them! If they repent, it will be best for them; but if they turn back (to their evil ways), Allah will punish them with a grievous penalty in this life and in the Hereafter: They shall have none on earth to protect or help them.

(28) Those who slander such of the believers as give themselves freely to (deeds of) charity, as well as such as can find nothing to give except the fruits of their labour,- and throw ridicule on them,- Allah will throw back their ridicule on them: and they shall have a grievous penalty.

(29) And there were, among the desert Arabs (also), men who made excuses and came to claim exemption; and those who were false to Allah and His Messenger (merely) sat inactive. Soon will a grievous penalty seize the Unbelievers among them.

(30) Certain of the desert Arabs round about you are hypocrites, as well as (desert Arabs) among the Medina folk: they are obstinate in hypocrisy: thou knowest them not: We know them: twice shall We punish them: and in addition shall they be sent to a grievous penalty.