The Prophet Muhammad on Generosity
If anyone gives as charity as little as a date that has been lawfully earned, God will accept it with His right hand, then nurture it on behalf of the one who gave it in the same way that one of you nurtures a colt, till it becomes like a mountain.
Every act of kindness is an act of charity... Do not consider any act of kindness insignificant, even meeting another with a cheerful face.
Worship the Compassionate One, provide food, and greet everyone you meet, and you will enter paradise in peace.
The most excellent charity consists in your satisfying a hungry stomach.
When Aisha asked the Prophet what things were unlawful to refuse, he replied, "Water, salt and fire. To those who give fire, it is as if they had given in charity everything cooked by that fire. To those who give salt, it is as if they had given in charity everything freshened by that salt. To those who give water where water is found, it is as if they had freed a slave. To those who give water where there is none, it is as if they had given the thirsty one life."
from Serving the Guest: A Sufi Cookbook