How can profit from forex trading, resulting from leverage, be purified, and income from an interest-based loan from a bank be purified, and can a salary that passes through an interest-based bank be purified?

Usury (Riba) is greatly forbidden. Financial leverage is a loan from a brokerage firm to a client on condition that transactions are conducted through it. This brings benefit to the lender, which makes it forbidden. Whoever deals with it commits a sin and must repent by ceasing it, seeking forgiveness, feeling remorse, and resolving not to return to it. The prohibition of an usurious loan pertains to the borrower's liability, not to the money itself. So, if he invests it and profits, or buys with it, benefiting from the profit and the items is permissible, and he is not required to give anything in charity; because the loan enters into the ownership of the borrower and becomes a debt upon him, and the borrower sins for dealing with usury and must repent. The passage of salary through an usurious bank does not affect its lawfulness if the work itself is permissible, and it is permissible to benefit from it, unless an usurious interest is given on it, in which case only the interest must be disposed of by giving it to the poor and needy, while the original salary remains lawful.