In the emphasis on the economic efficiency of the use of natural resources, either for consumption or production, we find Islam is differentiating clearly between two important notions: isràf and tabzìr. This has been mentioned in the Quranic verses with a particular distinction between the two.
In consumption for example, isràf could be interpreted as extending the level of consumption beyond the level of basic needs. This may lead to, and incorporates, the consumption of luxurious goods and services. In terms of the relationship between saving and spending, isràf may also be widened to include sacrificing future consumption, saving, for the sake of immediate consumption, and spending; which is a reflection of the consumer’s time preference in allocating his consumption between present and future income. In this case the balance between the two types of consumption, in both cases, first, the basic needs as compared with luxurious consumption, and second, future as compared to present consumption, which good Muslims are required to observe, may be impaired. This is not recommended; it is frowned upon and may even attract God’s dissatisfaction. But the punishment for this behaviour, is not, as it seems from reading the Quranic verses, as severe as the punishment associated with another level of consumption, tabzìr.
Tabzìr in an economic sense is the unnecessary use of economic resources, i.e. wastage of economic resources, large or small, and at all levels of consumption. Tabzìr, is not confined to the level of extravagance, but goes beyond that to include even the level of necessities if the consumer was wasteful in satisfying his or her very basic needs of these essential physio-sociological wants. To put it another way, one may have a variety of suits, meals, electrical appliances, and may in that reach the level of extravagance, which, to remind ourselves, is frowned upon and may even attract a penalty subject to the ability of economic resources and the development state of the economy, but one may not waste fabric or food ingredients
unnecessarily in having even one modest suit or eating one meal. Wastage, tabzìr, even in fulfilling most basic needs is forbidden. Therefore, while isràf is the extensive use of resources, tabzìr is the wasteful use of these resources; and there is a distinct line between the two. While the former may lead to further comfort, better appearance and, most likely, more pleasure in life, the latter leads to no purpose but wasting valuable resources to the community and the world by putting these resources to no use. The former may make one less of a perfect Muslim, but the latter would render a person irresponsible to the point of evil: a brother of Satan, “Verily resource wasters (mubazzirìn) are brethren to Satan, and Satan is the worst
unbeliever”, (Quran 17:27). Tabzìr attracts the wrath of God, for which the penalty is His retribution.
Islamic Economics. A Short History (Themes in Islamic Studies) by Ahmed El-Ashker, Rodney Wilson