Charity is proof
الصَّدَقَةُ بُرْهَانٌ
As-sadaqatu burhan.
"Charity is a proof [of faith]."
Narrated by Abu Malik al-Ash'ari. Sahih Muslim 223
A short reflection
Everyone can claim to believe. The one who hands money over when he could have kept it, his claim is exhibited, not just stated.