﴿ خُذْ مِنْ أَمْوَٰلِهِمْ صَدَقَةًۭ تُطَهِّرُهُمْ وَتُزَكِّيهِم بِهَا وَصَلِّ عَلَيْهِمْ ۖ إِنَّ صَلَوٰتَكَ سَكَنٌۭ لَّهُمْ ۗ وَٱللَّهُ سَمِيعٌ عَلِيمٌ ﴾

“[Hence, O Prophet,] accept that [part] of their possessions which is offered for the sake of God, so that thou mayest cleanse them thereby and cause them to grow in purity, and pray for them: behold, thy prayer will be [a source of] comfort to them-for God is all-hearing, all-knowing.”

Allah then explained to the Prophet (pbuh) what he should take of their wealth because they had asked him to take some of it because they had stayed behind and not taken part in the Battle of Tabuk. But the Prophet (pbuh) initially refused to take anything from them until, that is, Allah explained the matter to him, saying: (Take alms) a third (of their wealth) the wealth of those who stayed behind, wherewith thou mayst purify them) from their sins (and mayst make them grow) and reform them with it, (and pray for them) ask forgiveness for them and make supplication for them. (Lo! Your prayer) your asking for their forgiveness and your supplications (is an assuagement for them) tranquillity for their hearts that their repentance will be accepted. (Allah is Hearer) of what they say, i.e. their saying: take our wealth, (Knower) of their repentance and intention.