In the Quranic verse 47:38 Allah (swt) says:
‘Behold! You are those who are called to spend in the Cause of Allah, yet amongst you are some who are niggardly. And whoever is niggardly, it is only at the expense of his own self. But Allah is Rich (Free of all wants) and you (mankind) are poor. And if you turn away (from Islam and the obedience of Allah), He will exchange you for some other people. And they will not be your likes’.
In this verse Allah (swt) has Commanded us to spend a part of our wealth in His Way. The people who behave in a miserly way and abstain from sharing their wealth with the poor are actually depriving themselves of Allah (swt)’s Bounty. Allah (swt) has made it quite clear here that He does not Command us to give charity because He is in need of it. On the contrary Allah (swt) is Self-sufficient and does not require anyone’s help. He has Commanded the wealthy people to give charity because giving donation or charity of any kind proves to be beneficial for the donors, in three ways. First of all giving charity helps to purify one’s soul from many diseases, especially stinginess and selfishness. Secondly, it is a means of bridging the gap between the rich and the poor so there is peace and justice in the society. Thirdly, it helps the Muslims to dominate their enemies because if the rich help their poor fellow-beings then poverty will get eradicated and the society will flourish. As the saying goes, united we stand divided we fall, likewise when the rich people will co-operate with the poor people, the Muslims will be better placed in the society and they will become stronger as a community to ward off their enemies.
*Mu’aadh bin Jabal (ra) related from the Prophet (swt), ‘Sadaqah extinguishes sin as water extinguishes fire’.(Ahmed, Tirmidhi)
*Abu Huraira (ra) reported Prophet Mohammad (saw) as saying, ‘Charity does not in any way decrease the wealth; and the servant who forgives, Allah adds to his respect and the one who shows humility, Allah elevates him in the elevation (of the people)’. Muslim.
So these ahadith also make it clear that offering donation or charity is a great, risk-free deal by through which the donor does not lose anything but earns many brownie points in the long run.