Fiqh-us-Sunnah Volume 3, Zakaat and Fasting, Fiqh 3.097A.

Section : Zakat ut-Tatawwu or Voluntary Sadaqah in the Qur’an.

Allah, the Exalted One, says: “The parable of those who spend their wealth in the way of Allah is that of a grain of corn: it grows seven ears, and each ear has a hundred grains. Allah gives manifold increase to whom He pleases; Allah cares for all and knows all things” [al-Baqarah 261].

“By no means shall you attain righteousness unless you give freely of that which you love, and whatever you give, Allah knows it well” [al’Imran 92].

“And spend from what We have made you heir. For those of you who believe and spend, for them is a great reward” [alHadid 7].