The word(s) "duty" appears 64 time(s) in 61 verse(s) in Quran in Mohsin Khan translation.

(11) And warn therewith (the Qur'an) those who fear that they will be gathered before their Lord, when there will be neither a protector nor an intercessor for them besides Him, so that they may fear Allah and keep their duty to Him (by abstaining from committing sins and by doing all kinds of good deeds which He has ordained).

(12) He is the Irresistible, (Supreme) over His slaves, and He sends guardians (angels guarding and writing all of one's good and bad deeds) over you, until when death approaches one of you, Our Messengers (angel of death and his assistants) take his soul, and they never neglect their duty.

(13) Those who fear Allah, keep their duty to Him and avoid evil are not responsible for them (the disbelievers) in any case, but (their duty) is to remind them, that they may fear Allah (and refrain from mocking at the Qur'an). [The provision of this Verse was abrogated by the Verse 4:140].

(14) Verily, those who believed, and emigrated and strove hard and fought with their property and their lives in the Cause of Allah as well as those who gave (them) asylum and help, - these are (all) allies to one another. And as to those who believed but did not emigrate (to you O Muhammad صلى الله عليه وسلم), you owe no duty of protection to them until they emigrate ; but if they seek your help in religion, it is your duty to help them except against a people with whom you have a treaty of mutual alliance; and Allah is the All-Seer of what you do.

(15) As-Sadaqat (here it means Zakat ) are only for the Fuqara' (poor), and Al-Masakin (the poor) and those employed to collect (the funds), and to attract the hearts of those who have been inclined (towards Islam), and to free the captives, and for those in debt, and for Allah's Cause (i.e. for Mujahidun - those fighting in a holy battle), and for the wayfarer (a traveller who is cut off from everything); a duty imposed by Allah. And Allah is All-Knower, All-Wise.

(16) There is no blame on those who are weak or ill or who find no resources to spend [in holy fighting (Jihad)], if they are sincere and true (in duty) to Allah and His Messenger. No ground (of complaint) can there be against the Muhsinun (good-doers - See the footnote of V.9:120). And Allah is Oft-Forgiving, Most Merciful.

(17) Verily, in the alternation of the night and the day and in all that Allah has created in the heavens and the earth are Ayat (proofs, evidence, verses, lessons, signs, revelations, etc.) for those people who keep their duty to Allah, and fear Him much.

(18) And verily, the reward of the Hereafter is better for those who believe and used to fear Allah and keep their duty to Him (by abstaining from all kinds of sins and evil deeds and by performing all kinds of righteous good deeds).

(19) So, when they despaired of him, they held a conference in private. The eldest among them said: "Know you not that your father did take an oath from you in Allah's Name, and before this you did fail in your duty with Yusuf (Joseph)? Therefore I will not leave this land until my father permits me, or Allah decides my case (by releasing Benjamin) and He is the Best of the judges.

(20) Whether We show you (O Muhammad صلى الله عليه و سلم) part of what We have promised them or cause you to die, your duty is only to convey (the Message) and on Us is the reckoning.