The word(s) "grievous" appears 6 time(s) in 6 verse(s) in Quran in Muhammad Pickthal translation.

(1) Yet ye it is who slay each other and drive out a party of your people from their homes, supporting one another against them by sin and transgression? - and if they came to you as captives ye would ransom them, whereas their expulsion was itself unlawful for you - Believe ye in part of the Scripture and disbelieve ye in part thereof? And what is the reward of those who do so save ignominy in the life of the world, and on the Day of Resurrection they will be consigned to the most grievous doom. For Allah is not unaware of what ye do.

(2) And if their aversion is grievous unto thee, then, if thou canst, seek a way down into the earth or a ladder unto the sky that thou mayst bring unto them a portent (to convince them all)! - If Allah willed, He could have brought them all together to the guidance - So be not thou among the foolish ones.

(3) There hath come unto you a messenger, (one) of yourselves, unto whom aught that ye are overburdened is grievous, full of concern for you, for the believers full of pity, merciful.

(4) (The people of the city) said: We augur ill of you. If ye desist not, we shall surely stone you, and grievous torture will befall you at our hands.

(5) Know that the life of the world is only play, and idle talk, and pageantry, and boasting among you, and rivalry in respect of wealth and children; as the likeness of vegetation after rain, whereof the growth is pleasing to the husbandman, but afterward it drieth up and thou seest it turning yellow, then it becometh straw. And in the Hereafter there is grievous punishment, and (also) forgiveness from Allah and His good pleasure, whereas the life of the world is but matter of illusion.

(6) Lo! these love fleeting life, and put behind them (the remembrance of) a grievous day.