Indeed, these disbelievers love the immediate and prefer it over the Hereafter, as His saying: "Rather, you prefer the worldly life." Behind them is a heavy day that they do not care about, a day that is heavy due to its severity, and it is heavy for the one who carries it. Similar to this is: "It is heavy in the heavens and the earth." The term 'asr refers to binding and securing. From it comes: a man is 'asr' when he is bound by a cord, which is the 'isar.' A horse is 'masoor' in creation. A shield is 'masoor' by the ankle. The meaning is: We have tightened the connection of their bones to one another and secured their joints with nerves. It is similar to their saying: a girl bound in creation and braided. And if We will, We could destroy them and replace them with others in severe bondage, meaning: the other creation. It is said: We replaced them with others who obey. It is more appropriate that it comes with 'if' (in the sense of condition), not 'when,' as in His saying: "And if you turn away, He will replace a people other than you, and they will not be like you, if He wills, He could remove you."