What is the concept of extravagance (tabdhir) and prodigality (israf) in the Quran and Sunnah, and what are the reliable references that address this topic?

It is well-known that extravagance (isrāf) and squandering (tabdhīr) are synonymous, encompassing both words and actions. It has been said: Squandering is ignorance of the rightful places (of expenditure), and extravagance is ignorance of their proper measures. It has also been said: Extravagance is spending something on what is permissible but in excess of what is necessary, whereas squandering is spending something on what is impermissible. Another opinion states: Squandering is specific to spending money on acts of disobedience, while extravagance is exceeding the limit in money and other things. Both have been warned against in the texts of the Quran and Sunnah, such as His (Allah's) saying: "And do not squander wastefully. Indeed, squanderers are brothers of devils" (Quran 17:26-27), and His saying: "And eat and drink, but be not excessive. Indeed, He likes not those who are excessive" (Quran 7:31).