There are 5 Tenets (pillars or principles) of Islam, (i) Shahadah (Iman - faith), (ii) Salah (Distinctive Submission - a form of Islamic Prayer ), (iii) Zakah (Islamic Charity), (iv) Sawm (Islamic Fasting), (v) Hajj (Pilgrimage to Makkah).
It is in Hadith - Narrated by Ibn Umar (RU) - Allah's Apostle (SAWS) said - Islam is based on (the following) five (principles) - (i) 'there is no (real) god except Allah (SWT) and Mohammad (SAWS) is Allah's Apostle, (ii) to offer Salah ( prayers) dutifully and perfectly, (iii) to pay Zakat (Islamic charity), (iv) to perform Hajj (Pilgrimage to Makka), and (v) to observe fast during the month of Ramadhan. (Bukhari Book 2 Hadith 7 )
The Zakah is an obligatory charity for Muslims who have reached the age of puberty, are sane, free, and who own the minimum assigned wealth ( 85 grams of gold or 595 grams of pure silver or equivalent in cash or articles of trade). Muslims are required to pay 1/40th part of their surplus wealth to the designated needy, every lunar year.
Zakat is often described as purification of surplus wealth. The surplus wealth, in a given year, is the net balance amount, after we have spent on basic necessities, expenses, credits, and taxes. Zakah is generally given at the end of Hijri year or in the month of Ramadhan.
'Zakah' is mentioned in about 30 verses of Quran along with Salah, which shows its importance.
It is in Quran - "Establish Salah and give Zakah; and lend to Allah (SWT) a beautiful loan. And whatever good you send forth for your souls, you shall find it with Allah (SWT), better and greater in reward and you seek the grace of Allah (SWT); for Allah (SWT) is oft-forgiving, Most Merciful." (Al-Muuzammil - 20)
It is in Quran - "But (even so), if they repent; (and) establish Salah and Zakah, they are your brethren in Faith: (thus) do We explain the Signs in detail, for those who understand." (At-Tauba - 11)
It is in Quran - "They were enjoined only to worship Allah (SWT), sincere in their faith in Him alone - and of upright religion - and to establish the Salah and the Zakah. Such is the upright religion. (Al-Bayyana - 5)
It is in Quran - "Those who lay up treasures of gold and silver and spend them not in the way of Allah (SWT); give them the news of a painful punishment, on the Day when that (wealth) will be heated in hellfire, and their foreheads and their sides and their backs branded therewith: "This is the treasure which you laid up for yourselves! Taste, then, your hoarded treasure!" (At-Tauba -34/35).
It is in Quran - "Zakah is for the poor and the needy, and those employed to administer the (funds); for those whose hearts have been (recently) reconciled (to the truth); for those in bondage and in debt; in the cause of Allah (SWT); and for the wayfarer: (thus is it) ordained byAllah (SWT), and Allah (SWT). And Allâh is All-Knower, All-Wise.." (At-Tauba - 60)
It is in Quran - 'On that day their treasures will be heated in the fire of Hell and their foreheads, sides and back will be branded therewith. (They will be told) This is what you had hoarded for yourself. Now taste the penalty of such hoarding (9-35).
It is in Quran - 'And those who are miser in what has been given to them by Allah (SWT) by His grace should not think that it is good for them; on the contrary it is bad for them. The riches they have piled up shall become their necklace on the Day of Judgment. (3-180).It is in Hadith - The Prophet (SAWS) is reported to have said that there are 360 joints in a human body. Man should give charity for each of those joints. The Companions (RU) asked: 'O Prophet (SAWS) who has the ability to give so much charity? ' The Prophet (SAWS) replied: 'To clean any filth or dirt in the Masjid, or remove some harmful object from the road, is also charity. If you do not find something which would be a charity equivalent to the 360 joints, then the two Rakahs of Ishraq Salah will be enough for you.' (Mishkat, Abu Da'ud).
It is in Hadith - " To whoever Allah Subhana Wa Taala has given wealth and he did not fulfill his right from his wealth, his wealth on the Day of Qiyamah (Judgement Day) will take up the shape of a bald snake, - whose hair has fallen out because of its poison and who would have two black dots on its eyes. The snake will be made into his necklace and it will grab both jaws and say 'I am your wealth, I am your treasure'. " then the Prophet (SAWS) recited the verse (3:180) of Qur'an. (Bukhari ).
It is in Hadith - "For every wealth owner who did not fulfill his right from his wealth, his wealth will come on the day of Qiyamah in the shape of a bald snake, who will have its mouth open. When it comes close towards the wealth owner the wealth owner will run away from it. The snake will call out to him 'come take the wealth which you hid for I dont need it.' When the wealth owner (in despair) sees no other way he will put his hand into the mouth of the snake. The snake will chew his hand like a bull chews something. " (Muslim).
It is in Hadith - 'Two women wearing gold bracelets came into the presence of the Prophet (SAWS). The Prophet (SAWS) asked them, " Would you prefer that Allah (SWT) should give you bracelets of fire to wear on the day of Qiyamah ? " They replied, " No, O Blessed Prophet.(SAWS)" The Prophet (SAWS) replied, " So give what is your duty on what you have in your hands. " (Ahmad).