The word(s) "hard" appears 62 time(s) in 58 verse(s) in Quran in Muhammad Habib Shakir translation.

(41) And (as for) those who strive hard for Us, We will most certainly guide them in Our ways; and Allah is most surely with the doers of good.

(42) And (as for) those who strive hard in opposing Our communications, these it is for whom is a painful chastisement of an evil kind.

(43) And this is not hard to Allah.

(44) What! is he whose heart Allah has opened for Islam so that he is in a light from his Lord (like the hard-hearted)? Nay, woe to those whose hearts are hard against the remembrance of Allah; those are in clear error.

(45) And if We make him taste mercy from Us after distress that has touched him, he would most certainly say: This is of me, and I do not think the hour will come to pass, and if I am sent back to my Lord, I shall have with Him sure good; but We will most certainly inform those who disbelieved of what they did, and We will most certainly make them taste of hard chastisement.

(46) He has made plain to you of the religion what He enjoined upon Nuh and that which We have revealed to you and that which We enjoined upon Ibrahim and Musa and Isa that keep to obedience and be not divided therein; hard to the unbelievers is that which you call them to; Allah chooses for Himself whom He pleases, and guides to Himself him who turns (to Him), frequently.

(47) Nay! I am better than this fellow, who is contemptible, and who can hardly speak distinctly:

(48) And most certainly We will try you until We have known those among you who exert themselves hard, and the patient, and made your case manifest.

(49) The believers are only those who believe in Allah and His Apostle then they doubt not and struggle hard with their wealth and their lives in the way of Allah; they are the truthful ones.

(50) So turn (your) back on them (for) the day when the inviter shall invite them to a hard task,