It is extravagance to eat everything you desire. (Prophet of Islam, reported by Ibn Majah)

Every person lives between two things: needs, on the one hand, and desires, on the other. To spend your wealth on things that you need is a justified and legitimate use of it. But to spend it in order to fulfil your desires is an action that you will have to answer for, on the Day of Judgment.

Umar reiterated the same point when he said:

“It is enough for a person to be wasteful if he eats everything that his heart desires.” (Kanz ul-Ummal)

To waste your money is to spend it on something that you do not really need but that you simply desire.

In this matter, the right thing to do is that whenever you are faced with a situation that requires money to be spent, take time off to seriously think whether this is for something that you truly need or for something that you simply desire. If it is for a genuine need then decide in its favour. But if it is not really for a necessity but only a desire, then you should desist from spending on it.

To waste your money is to spend it on something that you do not really need but that you simply desire.

In this matter one needs to analyse each of one's wants. If one fails to do this even once, one may find oneself sliding down the slippery slope of wastefulness, and then it may be very difficult for one to retrieve oneself.