What is the ruling on money acquired from working in a usurious bank (for 15 years), and what branched out from it in terms of buying and selling, and end-of-service benefits? Is it permissible to give it to needy siblings?

Working in usurious banks is forbidden (haram) because it constitutes cooperation in sin and transgression, and its earnings are illicit (haram). Whoever has worked in a usurious bank must repent. The questioner has done well by leaving her job.

Regarding the earned salaries: - If the questioner knew that the work was forbidden: she must donate all that she received to charitable causes and for the benefit of Muslims. - If she was ignorant that the work was forbidden: there is no blame upon her for what was consumed from the salaries, but she must donate whatever remains with her (cash, gold, a car).

It is permissible to dispose of this money by spending it on needy relatives whose maintenance is not obligatory upon her (such as brothers who need money for marriage, treatment, education, or a home), provided that the needy person is given only what he needs and does not possess what can cover his need. If the questioner herself is in need (for maintenance, clothing, housing, or treatment), she may take from this money an amount sufficient for her needs.