How does God rule with justice among His servants, when He accepts the repentance of someone who lived a long life, compared to someone who died early and did not have the opportunity to repent?

A Muslim must believe that Allah does what He wills and ordains what He desires, that He is not to be questioned about what He does, and that He is just, never oppressing anyone. Furthermore, all His actions contain wisdom, which we may or may not comprehend. The lengthening or shortening of lifespans is for reasons known to Allah, and a shorter life may even be better for some. These are matters of the unseen, known only to Allah, and a Muslim should not preoccupy himself with them. Rather, he should be content with the certainty that Allah has not wronged anyone and should busy himself with acts of obedience.