The word(s) "hard" appears 35 time(s) in 32 verse(s) in Quran in Abdullah Yusuf Ali translation.

(1) Nay, seek (Allah's) help with patient perseverance and prayer: It is indeed hard, except to those who bring a lowly spirit,-

(2) And remember, We delivered you from the people of Pharaoh: They set you hard tasks and punishments, slaughtered your sons and let your women-folk live; therein was a tremendous trial from your Lord.

(3) Thenceforth were your hearts hardened: They became like a rock and even worse in hardness. For among rocks there are some from which rivers gush forth; others there are which when split asunder send forth water; and others which sink for fear of Allah. And Allah is not unmindful of what ye do.

(4) (Fasting) for a fixed number of days; but if any of you is ill, or on a journey, the prescribed number (Should be made up) from days later. For those who can do it (With hardship), is a ransom, the feeding of one that is indigent. But he that will give more, of his own free will,- it is better for him. And it is better for you that ye fast, if ye only knew.

(5) O ye who believe! cancel not your charity by reminders of your generosity or by injury,- like those who spend their substance to be seen of men, but believe neither in Allah nor in the Last Day. They are in parable like a hard, barren rock, on which is a little soil: on it falls heavy rain, which leaves it (Just) a bare stone. They will be able to do nothing with aught they have earned. And Allah guideth not those who reject faith.

(6) Did ye think that ye would enter Heaven without Allah testing those of you who fought hard (In His Cause) and remained steadfast?

(7) And slacken not in following up the enemy: If ye are suffering hardships, they are suffering similar hardships; but ye have Hope from Allah, while they have none. And Allah is full of knowledge and wisdom.

(8) But because of their breach of their covenant, We cursed them, and made their hearts grow hard; they change the words from their (right) places and forget a good part of the message that was sent them, nor wilt thou cease to find them- barring a few - ever bent on (new) deceits: but forgive them, and overlook (their misdeeds): for Allah loveth those who are kind.

(9) If their spurning is hard on thy mind, yet if thou wert able to seek a tunnel in the ground or a ladder to the skies and bring them a sign,- (what good?). If it were Allah's will, He could gather them together unto true guidance: so be not thou amongst those who are swayed by ignorance (and impatience)!

(10) When the suffering reached them from us, why then did they not learn humility? On the contrary their hearts became hardened, and Satan made their (sinful) acts seem alluring to them.