What is the ruling regarding this dinar that the customer refuses to pay, even though he had agreed to purchase the item beforehand, and requested its opening and installation, but then reneged on his promise, claiming he no longer needed it?

In conclusion, the ruling on breaking a promise to buy an item worth 12 dinars is subject to scholarly disagreement. The preponderant opinion is that it is binding, both judicially and religiously, if the promisee incurred a burden as a result of the promise, as decided by the Islamic Fiqh Academy. In this case, it appears that the questioner did not suffer any harm or burden due to the promise, and therefore she is not entitled to take the dinar.