What should a young man do with the money he earned from his previous job at a "Riba-based bank" after leaving it and repenting? Is repentance sufficient, or must he dispose of the money, such as by giving it away in charity?

Money earned from working in a usurious bank is unlawful due to its illicit nature. It should be spent on charitable causes and general Muslim welfare. Its possessor may take from it only what is necessary for their basic needs, such as housing, food, clothing, and transportation, provided they have no other source of permissible income.