The word(s) "duty" appears 12 time(s) in 12 verse(s) in Quran in Saheeh International translation.

(1) Prescribed for you when death approaches [any] one of you if he leaves wealth [is that he should make] a bequest for the parents and near relatives according to what is acceptable - a duty upon the righteous.

(2) Mothers may breastfeed their children two complete years for whoever wishes to complete the nursing [period]. Upon the father is the mothers' provision and their clothing according to what is acceptable. No person is charged with more than his capacity. No mother should be harmed through her child, and no father through his child. And upon the [father's] heir is [a duty] like that [of the father]. And if they both desire weaning through mutual consent from both of them and consultation, there is no blame upon either of them. And if you wish to have your children nursed by a substitute, there is no blame upon you as long as you give payment according to what is acceptable. And fear Allah and know that Allah is Seeing of what you do.

(3) There is no blame upon you if you divorce women you have not touched nor specified for them an obligation. But give them [a gift of] compensation - the wealthy according to his capability and the poor according to his capability - a provision according to what is acceptable, a duty upon the doers of good.

(4) And for divorced women is a provision according to what is acceptable - a duty upon the righteous.

(5) So if they argue with you, say, "I have submitted myself to Allah [in Islam], and [so have] those who follow me." And say to those who were given the Scripture and [to] the unlearned, "Have you submitted yourselves?" And if they submit [in Islam], they are rightly guided; but if they turn away - then upon you is only the [duty of] notification. And Allah is Seeing of [His] servants.

(6) So when they had despaired of him, they secluded themselves in private consultation. The eldest of them said, "Do you not know that your father has taken upon you an oath by Allah and [that] before you failed in [your duty to] Joseph? So I will never leave [this] land until my father permits me or Allah decides for me, and He is the best of judges.

(7) And whether We show you part of what We promise them or take you in death, upon you is only the [duty of] notification, and upon Us is the account.

(8) And those who associate others with Allah say, "If Allah had willed, we would not have worshipped anything other than Him, neither we nor our fathers, nor would we have forbidden anything through other than Him." Thus did those do before them. So is there upon the messengers except [the duty of] clear notification?

(9) Say, "Obey Allah and obey the Messenger; but if you turn away - then upon him is only that [duty] with which he has been charged, and upon you is that with which you have been charged. And if you obey him, you will be [rightly] guided. And there is not upon the Messenger except the [responsibility for] clear notification."

(10) And if you [people] deny [the message] - already nations before you have denied. And there is not upon the Messenger except [the duty of] clear notification.