The Holy Quran 3:141 — Surah Ali 'Imran

Arabic text

وَلِيُمَحِّصَ ٱللَّهُ ٱلَّذِينَ ءَامَنُوا۟ وَيَمْحَقَ ٱلْكَـٰفِرِينَ

Translation

(Referring to the Battle of Uhud, Allaah say that He alternates victory and defeat between nations) So that Allaah may purify the Mu'mineen (from their sins through suffering defeat) and destroy the Kaafiroon (when the Muslims defeat them).

Tafsir (excerpt) — Tafsir Usmani

That is, victory and defeat are changeable things; and [Allah] willed to grant the Muslims the high station of martyrdom, to test the believer and the hypocrite, to train the Muslims or cleanse them of sins, and to wipe out the disbelievers gradually: when they, delighted and puffed up by their temporary ascendancy and momentary success, go to ever greater…

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