The Cow - 2:129
Our Lord, send from among them a messenger who will recite to them Your Verses, teach them the Book and wisdom, and purify them. You are Exalted, Wise.
What do you mean by cleansing?
The Repentance/9:103
Take alms from their money to purify them and glorify them, and encourage them and support them, for your support pleases them. Allah is All-Hearing, All-Knowing.
The Cow/2:271
How good it would be if you revealed your charity. But it is better if you hide them and give them to the needy, and that will cover some of your sins. Allah is aware of what you do.
The Night/92:18
He who cleanses himself by giving his wealth;