The Holy Quran, the book of religions scriptures for Muslims, says in Surah 9:71:
"The believing men and women are allies of one another. They advocate righteousness and forbid evil, they observe the obligatory prayers (salat) and give the obligatory charity (zakat), and they obey GOD and His messenger. These will be showered by GOD's mercy. GOD is Almighty, Most Wise."
Zakat is the financial obligation upon all Muslims and is an important principal because its focus is upon giving in charity to those in need. The word “Zakah” in Arabic means both purification and growth, indicating that our giving of zakat is an act of purification and a facilitator of growth for the individual and for the community. Muslims understand and faithfully adhere to the principal that everything belongs to God, in Arabic Allah, and that any wealth that is bestowed or earned is entrusted to the believers from God. Zakat is one of the five pillars of Islam and very important because the setting aside of a portion of our possessions for others benefits society by addressing poverty.
The Holy Quran also states in Surah Al-Baqara, 2:215, “They ask thee what they should spend (in charity). Say: Whatever ye spend that is good, is for parents and kindred and orphans and those in want and for wayfarers. And whatever ye do that is good, -Allah knows it well.”
Each Muslim calculates his or her own zakat individually and it is usually submitted as an annual payment of a fortieth of one's capital, excluding such items as primary residence, car and professional tools. Believers can also give sadaqah, the non-obligatory charity, but this is preferably offered in secret.
The Prophet Muhammad, peace be upon him, said, "Even meeting your brother with a cheerful face is an act of charity."
“Among the five pillars of Islam, Muslims are also commanded to be charitable.
It is reported that the second Caliph, Umar ibn Al-Khattab said:
‘I heard the Messenger of Allah say, ‘Islam has been built upon five things – on testifying that there is no god save Allah, and that Muhammad is His Messenger; on performing salah (prayer); on giving the zakah (charity); on Hajj (pilgrimage to Makkah); and on fasting during Ramadan. (Al-Bukhari & Muslim)
In addition to the mandatory charity of zakah, Muslims are also enjoined toward voluntary charity (sadaqah), and incidentally, a smile is counted as an act of voluntary charity.”
Additional statements in the Holy Quran about Zakat read:
And be steadfast in prayer; practice regular charity; and bow down your heads with those who bow down (in worship). (Surah 2:43)
And remember We took a covenant from the Children of Israel (to this effect): Worship none but Allah; treat with kindness your parents and kindred, and orphans and those in need; speak fair to the people; be steadfast in prayer; and practice regular charity. Then did ye turn back, except a few among you, and ye backslide (even now). (Surah 2:83)
And be steadfast in prayer and regular in charity: And whatever good ye send forth for your souls before you, ye shall find it with Allah: for Allah sees Well all that ye do. (Surah 2:110)
It is not righteousness that ye turn your faces Towards east or West; but it is righteousness- to believe in Allah and the Last Day, and the Angels, and the Book, and the Messengers; to spend of your substance, out of love for Him, for your kin, for orphans, for the needy, for the wayfarer, for those who ask, and for the ransom of slaves; to be steadfast in prayer, and practice regular charity; to fulfill the contracts which ye have made; and to be firm and patient, in pain (or suffering) and adversity, and throughout all periods of panic. Such are the people of truth, the Allah-fearing. (Surah 2:177)