Sadaqah or Saddka is an Islamic term that means "voluntary charity". Sadaqah/Saddka on Quran:
Have you seen the one who denies the Religion? Such is he who repulses the orphan, and who does not urge others to feed the poor. Woe to worshippers, who are absent-minded to their prayer, those who make a show (of piety), and refuse to render small acts of kindness (towards others).(Al-Ma`un 107: 1-7)
And spend something (in charity) out of the substance which We have bestowed on you, before Death should come to any of you and he should say, “O my Lord! Why didst Thou not give me respite for a little while? I should then have given (largely) in charity, and I should have been one of the doers of good.” But to no soul will Allah grant respite when the time appointed (for it) has come; and Allah is well-acquainted with (all) that ye do. (Al-Munafiqun 63: 10-11)
Saddka should be given solely out of love for God, out of the desire to do good to His creation, as the Quran says about the righteous:"They give food, out of love for Him (Allah), to the poor, the orphan, and the slave, saying: We feed you only for Allah's pleasure - we desire from you neither reward nor thanks." (Qur’an76:8,9)
Giving Saddka will not diminish a Muslim's wealth. It serves as expiation for sins and yields rewards in the next life. Allah says: "For those who give in charity, men and women, and loan to Allah a Beautiful Loan, it shall be increased manifold (to their credit), and they shall have (besides) a liberal reward."(Qur'an 57:18).
The legitimacy of giving sadaqah other than that of Zakat is not restricted by a time limit or definite nisab. The amount designated for expenditure need not be a certain percentage (for example, a tithe, a one-quarter tithe, or a one-tenth tithe). It is an open-ended matter that is left to the beneficence, generosity, and condition of the one who gives. The protection of a revered (muhtaram) man from destruction and harm is an obligation upon whoever can help him, but more than that, it is left unquantified. People overlook most of the public rights which the Qur'an supports, for these rights seek to establish an honorable and just social life. People spend only a smalI amount on the needy and even less for beggars because they are considered the least deserving nowadays. This is due to the fact that beggars have made begging a profession (hirfah), even though most of them are well-to-do. Ibn Hazm says: "It is enjoined upon the rich of every country to support their poor, and the ruler has the authority to force them to do so. This is called for when the prescribed Zakat or the holdings of other Muslims are not enough to meet the needs of the poor. In that case, their food and their clothing to protect them from the elements and the eyes of the passer-by would be provided by the rich." The proof for this is in the saying of Allah, the Exalted One: "Give the kinsman his due, and the needy, and the wayfarer" [al-Isra' 26]. Allah also says: "[Show] kindness to parents, to near kin and orphans, to the needy, to relatives, to neighbors who are not related to you, to fellow travelers and wayfarers, and [to the slaves] whom your right hand possesses" [an-Nisa' 36]. Generosity urges support for the above-mentioned people and forbids harming them. Referring to the guilty in the life to come, the Qur'an says that they would ask each other: "What brought you to this hellfire?" They will answer: "We were not of those who prayed, nor did we feed the needy" [al-Muddaththir 42-44]. Thus, Allah links feeding the needy with performing prayers. According to the following hadith, related by authentic sources, the Messenger of Allah, upon whom be peace, said: "He who does not have mercy upon people, Allah's mercy will be kept from him." Anyone upon whom Allah bestowed His grace and who sees his Muslim brother hungry, in need of clothes, and miserable, and still does not help him, he will, indeed, deprive himself of Allah's mercy.
'Uthman an-Nahdi reported that 'Abdurrahman ibn Abi Bakr as-Siddiq informed him that the companions of as-Saffah were poor and that the Messenger of Allah, upon whom be peace, said: "He who has enough food for two, let him invite a third, and he who has food for four, let him invite a fifth or a sixth." It is related from Ibn 'Umar that the Messenger of Allah, upon whom be peace, said: "A Muslim is a brother of another, and he should neither do injustice to him nor betray him." Thus, anyone who lets a needy Muslim go without food or clothes while, in fact, he is able to feed and clothe him would have betrayed him. It is related from Abu Sa'id al-Khudri that the Messenger of Allah, upon whom be peace, said: "He whose holdings exceed his needs, let him support the one whose holdings do not, and he whose food exceeds his needs, let him share it with him who does not have food." Abu Sa'id al-Khudri says: "Then he mentioned so many kinds of property that we thought no one of us had the right to have anything surplus with us." his is the consensus of the companions, as it was reported by Abu Sa'id alKhudri. Concerning this tradition, it is reported on the authority of Abu Musa al-Ash'ari that the Prophet, upon whom be peace, said: "Feed the hungry, visit the sick, and ransom the prisoner." There are many 'ayahs in the Qur'an and numerous sound hadith on this subject. 'Umar says: "If I were to live again the past which I have already lived, I would take the surplus from the rich and distribute it among the poor immigrants (mujhajirun)." This is considered to be the most authentic report. 'Ali said: "Allah, the Exalted One, has placed a due upon the properties of the rich to meet the needs of the poor. Thus, if the poor go hungry or naked or struggle because of the neglect of the rich, then Allah will hold them [the rich] accountable on the Day of Judgment and will punish them." Ibn 'Umar is reported to have said: "There is a due on your property other than Zakat." It is related from 'Aishah (the mother of the believers), al-Hasan ibn 'Ali, Ibn 'Umar that all of them replied to those who had asked them: "If you are asked for help in cases of blood money, heavy debt, or desperate poverty, then it is a must for you to give them from your holdings."
It was accurately reported by Abu 'Ubaidah ibn al-Jarrah and 300 companions that (once) when their provisions had run very low, Abu 'Ubaidah ordered them to collect what was left and place it into two bags and then allot it to each one equally. Then he said: "It is not permissible for a hard-pressed Muslim to eat the meat of a dead animal or a pig when he can find surplus food from either a Muslim or a dhimmi. It is an obligation of the one who has food to feed the hungry." This has the consensus among the companions, and there are no contrary views concerning it. It was accurately reported from ashShu'bi, Mujahid, Tawus, and others that: "There is a due on property other than Zakat." If such is the case, then a hard-pressed person is not forced to eat the meat of dead animals or pigs. He has the right to fight for it and, if he is killed, then retaliation by killing (qawad) will be imposed upon the killer. If the property holder who prevents him from receiving his due is killed, then may he have the curse of Allah upon him because he withheld a right (haqq), and he will be regarded as being among the unjust. Allah, the Exalted One, says: "And if one party of them does wrong to the other, fight those who do wrong until they return to the ordinance of Allah." Thus, one who withholds a right is an oppressor of his brother. The latter is the possessor of that right. On this basis, Abu Bakr as-Siddiq waged war against those who refused to pay their Zakat. From the preceding, one can see the degree of compassion and commiseration that Islam has for the deprived. Islam, in fact, excels over all other faiths and systems. They are like weak, sputtering candles when placed next to the bright and steady light of the sun of Islam. The Insolvent Debtor Whoever has property must pay its proper Zakat. If the property is indebted, he may first pay off his debt, then in case the remainder is enough to constitute a nisab, he must pay Zakat. If he does not hold the nisab, he does not have to pay it since he is poor. The Messenger of Allah, upon whom be peace, said: "Only the wealthy are required to give charity." This hadith is related by Ahmad and al-Bukhari. The latter records it in mu'allaq form. The Prophet also said: "Zakat is levied on the rich and paid to the poor." It is all the same, whether he is indebted to Allah or to man, because one hadith states: "Allah's debt is more deserving of fulfillment.