Varying fortunes could be the fate of people involved in struggle; it is a test of resilience ordained by Allah (SwT) the test to judge those who believe, so as to take witnesses to truth, as laid down in the Holy Verse, noted below:
”If a wound hath touched you, be sure a similar wound hath touched the others. Such days (of varying fortunes) We give to men and men by turns: that Allah may know those who believe, and that He may take to Himself from your ranks martyr-witnesses (to Truth) And Allah loveth not those that do wrong” (Al Imran: 140)
Though the Holy Verse has general application, it alludes to the particularly to Ghazva-e-Uhud (battle of Uhud) where Muslims apparently faced a reverse, however the general application holds—any reverse in a struggle may not be taken as fait-accompli, as it holds that you might have taken a wound, the adversary too has taken a wound. In the saga of varying fortunes, the men are tested in turns. It is a test of belief, so that Allah (SwT) may judge the ones that believe. The ones who believe are taken as witnesses to Truth, the Truth that holds, whatever the pattern of tests that Allah (SwT) may hold and however varying might be the fortunes. In the events that unfold, one fact stands out—Allah (SwT) loveth not the ones that do wrong.
Success or failure may come, as in success humility should hold, failure may not be taken as an occasion to grumble. Success or failure may be taken in stride, holding the belief that it is part of Allah (SwT)’s overall plan, wherein in the ultimate analysis, the Truth will hold and falsehood, whatever its apparent strength will vanish, as Allah (SwT) loveth not the ones that do wrong.