The word(s) "observing" appears 3 time(s) in 3 verse(s) in Quran in Mohsin Khan translation.

(1) O you who believe! observing As-Saum (the fasting) is prescribed for you as it was prescribed for those before you, that you may become Al-Muttaqun (the pious - See V.2: 2).

(2) [observing Saum (fasts)] for a fixed number of days, but if any of you is ill or on a journey, the same number (should be made up) from other days. And as for those who can fast with difficulty, (e.g. an old man), they have (a choice either to fast or) to feed a Miskin (poor person) (for every day). But whoever does good of his own accord, it is better for him. And that you fast is better for you if only you know.

(3) And perform properly (i.e. all the ceremonies according to the ways of Prophet Muhammad صلى الله عليه وسلم), the Hajj and 'Umrah (i.e. the pilgrimage to Makkah) for Allah. But if you are prevented (from completing them), sacrifice a Hady (animal, i.e. a sheep, a cow, or a camel) such as you can afford, and do not shave your heads until the Hady reaches the place of sacrifice. And whosoever of you is ill or has an ailment in his scalp (necessitating shaving), he must pay a Fidyah (ransom) of either observing Saum (fasts) (three days) or giving Sadaqah (charity - feeding six poor persons) or offering sacrifice (one sheep). Then if you are in safety and whosoever performs the 'Umrah in the months of Hajj before (performing) the Hajj, (i.e. Hajj-at-Tamattu' and Al-Qiran), he must slaughter a Hady such as he can afford, but if he cannot afford it, he should observe Saum (fasts) three days during the Hajj and seven days after his return (to his home), making ten days in all. This is for him whose family is not present at Al-Masjid-Al-Haram (i.e. non-resident of Makkah). And fear Allah much and know that Allah is Severe in punishment.