The word(s) "duty" appears 86 time(s) in 79 verse(s) in Quran in Muhammad Habib Shakir translation.

(31) O you who believe! do not take for guardians those who take your religion for a mockery and a joke, from among those who were given the Book before you and the unbelievers; and be careful of (your duty to) Allah if you are believers.

(32) And eat of the lawful and good (things) that Allah has given you, and be careful of (your duty to) Allah, in Whom you believe.

(33) On those who believe and do good there is no blame for what they eat, when they are careful (of their duty) and believe and do good deeds, then they are careful (of their duty) and believe, then they are careful (of their duty) and do good (to others), and Allah loves those who do good (to others).

(34) Lawful to you is the game of the sea and its food, a provision for you and for the travellers, and the game of the land is forbidden to you so long as you are on pilgrimage, and be careful of (your duty to) Allah, to Whom you shall be gathered.

(35) Say: The bad and the good are not equal, though the abundance of the bad may please you; so be careful of (your duty to) Allah, O men of understanding, that you may be successful.

(36) This is more proper in order that they should give testimony truly or fear that other oaths be given after their oaths; and be careful of (your duty to) Allah, and hear; and Allah does not guide the transgressing people.

(37) When the disciples said: O Isa son of Marium! will your Lord consent to send down to us food from heaven? He said: Be careful of (your duty to) Allah if you are believers.

(38) And that you should keep up prayer and be careful of (your duty to) Him; and He it is to Whom you shall be gathered.

(39) And do not approach the property of the orphan except in the best manner until he attains his maturity, and give full measure and weight with justice-- We do not impose on any soul a duty except to the extent of its ability; and when you speak, then be just though it be (against) a relative, and fulfill Allah's covenant; this He has enjoined you with that you may be mindful;

(40) And (as for) those who believe and do good We do not impose on any soul a duty except to the extent of its ability-- they are the dwellers of the garden; in it they shall abide.