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

(51) O you who believe! Fear Allah and keep your duty to Him. And let every person look to what he has sent forth for the morrow, and fear Allah. Verily, Allah is All-Aware of what you do.

(52) Obey Allah, and obey the Messenger (Muhammad صلى الله عليه وسلم); but if you turn away, then the duty of Our Messenger is only to convey (the Message) clearly.

(53) So keep your duty to Allah and fear Him as much as you can; listen and obey, and spend in charity; that is better for yourselves. And whosoever is saved from his own covetousness, then they are the successful ones.

(54) Then when they are about to attain their term appointed, either take them back in a good manner or part with them in a good manner. And take as witness two just persons from among you (Muslims). And establish the testimony for Allah. That will be an admonition given to him who believes in Allah and the Last Day. And whosoever fears Allah and keeps his duty to Him, He will make a way for him to get out (from every difficulty).

(55) And those of your women as have passed the age of monthly courses, for them the 'Iddah (prescribed period), if you have doubt (about their periods), is three months; and for those who have no courses [(i.e. they are still immature) their 'Iddah (prescribed period) is three months likewise, except in case of death] . And for those who are pregnant (whether they are divorced or their husbands are dead), their 'Iddah (prescribed period) is until they lay down their burden; and whosoever fears Allah and keeps his duty to Him, He will make his matter easy for him.

(56) That is the Command of Allah, which He has sent down to you; and whosoever fears Allah and keeps his duty to Him, He will expiate from him his sins, and will enlarge his reward.

(57) Allah has prepared for them a severe torment. So fear Allah and keep your duty to Him, O men of understanding who have believed! Allah has indeed sent down to you a Reminder (this Qur'an).

(58) And be patient for the sake of your Lord (i.e. perform your duty to Allah)!

(59) Therefore be patient (O Muhammad صلى الله عليه وسلم) with constancy to the Command of your Lord (Allah, by doing your duty to Him and by conveying His Message to mankind), and obey neither a sinner nor a disbeliever among them.

(60) What does it matter to you if he will not become pure (from disbelief: you are only a Messenger, your duty is to convey the Message of Allah).