Waqf

The practice of declaring property as waqf may also have its origins in the ancient Islamic estate law, whereby a man's property reverted to the nation's ruler upon the man's death, unlike in other cultures wherein a man's descendants or designees inherit. By declaring his estate as waqf and his descendants as trustees, a rich man could provide an income for his surviving family.

Links:

• encyclopedia article (http://i-cias.com/e.o/waqf.htm)