Benefits of giving Zakaah & Sadaqah

Allaah تعالى says:

 وَمَا أَنفَقْتُم مِّن شَيْءٍ فَهُوَ يُخْلِفُهُ وَهُوَ خَيْرُ الرَّازِقِينَ 

...

{And whatsoever you spend of anything (in Allaah’s cause), He will replace it. And He is the best of providers.}

[Surah as-Saba’ (34): 39]

Imam Ibn Katheer رحمه الله says in his Tafseer (interpretation) of the above mentioned verse: "Whatever you spend in the ways that Allaah سبحانه و تعالى has commanded you and permitted you, He will compensate you for it in this world by giving you something else instead and in the Hereafter by giving you reward."

Narrated Abu Hurairah: The Prophet صلى الله عليه وسلم said, "Every day two angels come down from Heaven and one of them says, 'O Allaah! Compensate every person who spends in Your cause,' and the other (angel) says, 'O Allaah! Destroy every miser.'"

[Sahih Al-Bukhari, Vol. 2, Kitab az-Zakat, Hadith 522 and Sahih Muslim]

The Prophet صلى الله عليه وسلم also said: "You gain no victory or livelihood except through (the blessings and invocations of) the poor amongst you." [Sahih al-Bukhari, Vol. 4, Kitab al-Jihad, Hadith 145 and Sunan Nasa’i]