The word(s) "duty" appears 132 time(s) in 121 verse(s) in Quran in Muhammad Pickthal translation.

(51) Say: Come, I will recite unto you that which your Lord hath made a sacred duty for you: That ye ascribe no thing as partner unto Him and that ye do good to parents, and that ye slay not your children because of penury - We provide for you and for them - and that ye draw not nigh to lewd things whether open or concealed. And that ye slay not the life which Allah hath made sacred, save in the course of justice. This He hath command you, in order that ye may discern.

(52) And Moses said unto his people: Seek help in Allah and endure. Lo! the earth is Allah's. He giveth it for an inheritance to whom He will. And lo! the sequel is for those who keep their duty (unto Him).

(53) They ask thee (O Muhammad) of the spoils of war. Say: The spoils of war belong to Allah and the messenger, so keep your duty to Allah, and adjust the matter of your difference, and obey Allah and His messenger, if ye are (true) believers.

(54) O ye who believe! If ye keep your duty to Allah, He will give you discrimination (between right and wrong) and will rid you of your evil thoughts and deeds, and will forgive you. Allah is of Infinite Bounty.

(55) What (plea) have they that Allah should not punish them, when they debar (His servants) from the Inviolable Place of Worship, though they are not its fitting guardians. Its fitting guardians are those only who keep their duty to Allah. But most of them know not.

(56) Those of them with whom thou madest a treaty, and then at every opportunity they break their treaty, and they keep not duty (to Allah).

(57) Now enjoy what ye have won, as lawful and good, and keep your duty to Allah. Lo! Allah is Forgiving, Merciful.

(58) Lo! those who believed and left their homes and strove with their wealth and their lives for the cause of Allah, and those who took them in and helped them: these are protecting friends one of another. And those who believed but did not leave their homes, ye have no duty to protect them till they leave their homes; but if they seek help from you in the matter of religion then it is your duty to help (them) except against a folk between whom and you there is a treaty. Allah is Seer of what ye do.

(59) Excepting those of the idolaters with whom ye (Muslims) have a treaty, and who have since abated nothing of your right nor have supported anyone against you. (As for these), fulfil their treaty to them till their term. Lo! Allah loveth those who keep their duty (unto Him).

(60) How can there be a treaty with Allah and with His messenger for the idolaters save those with whom ye made a treaty at the Inviolable Place of Worship? So long as they are true to you, be true to them. Lo! Allah loveth those who keep their duty.