This is a very enlightening booklet by Abdul Malik Al-Qasim, a renowned religious scholar. There are many Ayat, Ahadith and good advices that encourage spending in the cause of Allah, thus opening the door wide to earning all that is good and righteous. Here are some examples:
Sadaqah (charity) shades its giver from the intense hear then.
It makes one's reckoning lighter. It makes one's Mizan (scale of good deeds) heavier Sadaqah helps cross over the Sirat.
Sadaqah elevates one's grade in Paradise.
It will be sufficient to encourage wise people to feel eager to give it.
Ibn Al-Qayyim said: Sadaqah saves from Allah's torment, for even though the slave's sins and mistakes direct him to destruction, Sadaqah steps in and saves and ransoms him from the torment.