The word(s) "hard" appears 36 time(s) in 35 verse(s) in Quran in Muhammad Pickthal translation.

(1) Seek help in patience and prayer; and truly it is hard save for the humble-minded,

(2) Then, even after that, your hearts were hardened and became as rocks, or worse than rocks, for hardness. For indeed there are rocks from out which rivers gush, and indeed there are rocks which split asunder so that water floweth from them. And indeed there are rocks which fall down for the fear of Allah. Allah is not unaware of what ye do.

(3) And they say: Our hearts are hardened. Nay, but Allah hath cursed them for their unbelief. Little is that which they believe.

(4) Thus We have appointed you a middle nation, that ye may be witnesses against mankind, and that the messenger may be a witness against you. And We appointed the qiblah which ye formerly observed only that We might know him who followeth the messenger, from him who turneth on his heels. In truth it was a hard (test) save for those whom Allah guided. But it was not Allah's purpose that your faith should be in vain, for Allah is Full of Pity, Merciful toward mankind.

(5) The month of Ramadan in which was revealed the Qur'an, a guidance for mankind, and clear proofs of the guidance, and the Criterion (of right and wrong). And whosoever of you is present, let him fast the month, and whosoever of you is sick or on a journey, (let him fast the same) number of other days. Allah desireth for you ease; He desireth not hardship for you; and (He desireth) that ye should complete the period, and that ye should magnify Allah for having guided you, and that peradventure ye may be thankful.

(6) Then because of their breaking of their covenant, and their disbelieving in the revelations of Allah, and their slaying of the prophets wrongfully, and their saying: Our hearts are hardened - Nay, but Allah set a seal upon them for their disbelief, so that they believe not save a few -

(7) And because of their breaking their covenant, We have cursed them and made hard their hearts. They change words from their context and forget a part of that whereof they were admonished. Thou wilt not cease to discover treachery from all save a few of them. But bear with them and pardon them. Lo! Allah loveth the kindly.

(8) If only, when Our disaster came on them, they had been humble! But their hearts were hardened and the devil made all that they used to do seem fair unto them!

(9) The wandering Arabs are more hard in disbelief and hypocrisy, and more likely to be ignorant of the limits which Allah hath revealed unto His messenger. And Allah is Knower, Wise.

(10) Allah hath turned in mercy to the Prophet, and to the Muhajirin and the Ansar who followed him in the hour of hardship. After the hearts of a party of them had almost swerved aside, then turned He unto them in mercy. Lo! He is Full of Pity, Merciful for them.