The word(s) "decline" appears 5 time(s) in 5 verse(s) in Quran in Mohsin Khan translation.

(1) Say: If your fathers, your sons, your brothers, your wives, your kindred, the wealth that you have gained, the commerce in which you fear a decline, and the dwellings in which you delight are dearer to you than Allah and His Messenger, and striving hard and fighting in His Cause, then wait until Allah brings about His Decision (torment). And Allah guides not the people who are Al-Fasiqun (the rebellious, disobedient to Allah).

(2) Have you not seen how your Lord spread the shadow. If He willed, He could have made it still - But We have made the sun its guide (i.e. after the sunrise, the shadow shrinks and vanishes at midnoon and then again appears in the afternoon with the decline of the sun, and had there been no sunlight, there would have been no shadow).

(3) And His are all the praises and thanks in the heavens and the earth; and (glorify Him) in the afternoon (i.e. offer 'Asr prayer) and when you come up to the time, when the day begins to decline (i.e. offer Zuhr prayer). (Ibn 'Abbas said: "These are the five compulsory congregational prayers mentioned in the Qur'an)." [Tafsir At-Tabari]

(4) Truly, We did offer Al-Amanah (the trust or moral responsibility or honesty and all the duties which Allah has ordained) to the heavens and the earth, and the mountains, but they declined to bear it and were afraid of it (i.e. afraid of Allah's Torment). But man bore it. Verily, he was unjust (to himself) and ignorant (of its results).

(5) And to Solomon (We subjected) the wind, its morning (stride from sunrise till midnoon) was a month's (journey), and its afternoon (stride from the midday decline of the sun to sunset) was a month's (journey i.e. in one day he could travel two months' (journey). And We caused a fount of (molten) brass to flow for him, and there were jinn that worked in front of him, by the Leave of his Lord. And whosoever of them turned aside from Our Command, We shall cause him to taste of the torment of the blazing Fire.