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

(31) "So fear Allah, keep your duty to Him, and obey me.

(32) "So fear Allah, keep your duty to Him, and obey me.

(33) "So fear Allah, keep your duty to Him, and obey me.

(34) "So fear Allah, keep your duty to Him, and obey me.

(35) And We saved those who believed, and used to fear Allah, and keep their duty to Him.

(36) "And if you deny, then nations before you have denied (their Messengers). And the duty of the Messenger is only to convey (the Message) plainly."

(37) O mankind! Be afraid of your Lord (by keeping your duty to Him and avoiding all evil), and fear a Day when no father can avail aught for his son, nor a son avail aught for his father. Verily, the Promise of Allah is true: let not then this (worldly) present life deceive you, nor let the chief deceiver (Satan) deceive you about Allah.

(38) O Prophet (Muhammad صلى الله عليه وسلم)! Keep your duty to Allah, and obey not the disbelievers and the hypocrites (i.e., do not follow their advice). Verily, Allah is Ever All-Knower, All-Wise.

(39) O wives of the Prophet! You are not like any other women. If you keep your duty (to Allah), then be not soft in speech, lest he in whose heart is a disease (of hypocrisy, or evil desire for adultery) should be moved with desire, but speak in an honourable manner.

(40) It is no sin on them (the Prophet's wives, if they appear unveiled) before their fathers, or their sons, or their brothers, or their brother's sons, or the sons of their sisters, or their own (believing) women, or their (female) slaves. And (O ladies), fear (keep your duty to) Allah. Verily, Allah is Ever All-Witness over everything.