The giving of property in excess of the due zakah is considered one of the basic elements of piety (birr) and is enjoined like the prescribed zakah.”
Whenever the exigency calls for it, sadaqah other than zakah is given. That could be before the completion of the year (hawl) or after the payment of zakah. The contribution is not based on a specific amount of nisab but on the ability to give. Thus, if someone possesses only a loaf of bread and sees a person who is more hard-pressed than himself, he should give it to that person. The hard-pressed person is not the only one who has a right to be satisfied, but Allah has also ordered the believers to give non-prescribed sadaqat to the following: kin, orphans, needy, wayfarers, beggars, and slaves.
Volume 3, Page 92: Kin (zhawi al-Qurba), recipients of sadaqah
The kin are considered the most deserving people for the sadaqah gift because of the common blood relationship. When a man is in need and some of his relatives are rich, naturally he looks to them for help because they are of one family. Also, it is natural for a man to feel more sympathy and pain with his hard-pressed and needy relatives than with strangers. He is humiliated by their degradation and elevated by their honor. Therefore, any well-to-do person who cuts off his kin from assistance and lives in luxury while his relatives are in a state of misery is devoid of natural feeling or lacks belief and is far away from goodness or piety. On the other hand, for one who maintains close links with his kin, his sustenance is assured and his relationship is of beneficence to his kin.
Volume 3, Page 92a: Orphans (wal-yatama), recipients of sadaqah
In the case of orphans whose guardians have died, their support and upbringing depends on wealthy and well to-do Muslims so that they will not become a problem to themselves or other people.
Volume 3, Page 92b: The Needy (wal-masakin), recipients of sadaqah
Because they are unable to earn enough to maintain themselves and have become contented with the little they have and abstain from begging, it is necessary for the well-to-do to help them.
Volume 3, Page 93: Wayfarere (wab nisabil), recipients of sadaqah
In the case of the wayfarer cut off from family and relatives, as if traveling were his household, consideration requires kindness for him as well. Thus, to sympathize with him and help him in his travels is, within the meaning of Islamic law, an encouragement which invites one to journey throughout the earth.
Volume 3, Page 93a: Beggars (was-sa’ilin), recipients of sadaqah
In the case of beggars forced to ask people for their needs, they should be helped. A person may also ask for help in order to redress another’s need. However, the shari’ah does not approve of begging, except under dire circumstances. Even then, one should not trespass limits.
Volume 3, Page 93b: Slaves (wa fi ar-riqab), recipients of sadaqah
The liberation of slaves includes buying and setting them free, helping contracted slaves (al-mukatabun) pay off their debts, and helping captives buy their way out of captivity. By encouraging people to spend out of their wealth on slaves, the shari ‘ah wants to emancipate the latter. Still, as important as the emancipation of slaves is, in terms of priorities, it is placed at the end, after the orphans, the needy, the wayfarer, and the beggar, the reason being that the former fall under the need for preserving life (which has a higher value), while the latter falls under the right to freedom (a lesser value than life).
Volume 3, Page 93c: Sadaqah other then Zakat
The legitimacy of giving sadaqah other than that of zakah 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.
Fiqh-us-Sunnah, Volume 3: Zakat ul-Fitr