Whatever you give or spend in the way of Allah will be returned to you in manifold increase. Allah, the most Bountiful and the most Loving, commends:

Lend unto God a goodly loan. Whatever good you shall forward on your behalf you shall find it with God, as better and richer in reward. [al-Muzzammil 73: 20.]

Prophet, sallallaahu `alayhi wa sallam ( may Allaah exalt his mention ), said:

A generous person is close to Allah, close to Paradise, close to people, and far from Hell. However, a miserly person is far from Allah, far from Paradise, far from people, but close to Hell. Allah loves more an ignorant man who is generous than a worshipper who is miserly. (Tirmidhi.)

Prophet, sallallaahu alayhi wa sallam ( may Allaah exalt his mention ), said: This worldly life is for four categories of people: a man to whom Allaah has given wealth and knowledge, so he fears his Lord, maintains ties of kinship with this money, and he knows the rights of Allaah regarding it, this one is truly in the best rank ... [At-Tirmithi]

The example of those who spend their wealth in the way of Allah is like a seed [of grain] which grows seven spikes; in each spike is a hundred grains. And Allah multiplies [His reward] for whom He wills. And Allah is all-Encompassing and knowing. This is the nature of making business with Allah (Quran 61:11), up to 700 times reward and the return is guaranteed.

If you disclose your charity, it is well; but if you conceal it and give it to the poor, that is better for you. [Allah] will expiate some of your sins. And Allah is well-acquainted with all that you do. (Surah al-Baqarah:271)

The Messenger of Allaah (peace and blessings of Allaah be upon him) said: The good deeds that will reach a believer after his death are: knowledge which he learned and then spread; a righteous son whom he leaves behind; a copy of the Quraan that he leaves as a legacy; a mosque that he built; a house that he built for wayfarers; a canal that he dug; or charity that he gave during his lifetime when he was in good health. These deeds will reach him after his death. Classed as hasan by al-Albaani in Saheeh Ibn Maajah.